JamesMitchell

For those that want to get straight to the parts and procedures, please scroll down to

Parts List:
Tools I Used:
and the procedures:
I. Expansion Valve Removal/Reinstallation:
II. A/C Compressor Removal/Reinstallation:
III. Receiver Drier Removal/Reinstallation:
IV. Recharging A/C System with New Freon:

Background:
I got inspired to do my own A/C repair from Mefferso’s excellent thread about his experience here:
https://mbworld.org/forums/gl-class-...ement-diy.html
I had done the Arnott strut repair and a few other DIY repairs, but I’ve always been reluctant to do anything with the A/C on any of my cars. But after reading Mefferso’s thread and some of the contributors to his thread, I got motivated to do my own. I purchased my 2007 GL450 new and it had never had any A/C work over the past 10 yrs. The right cylinder head needed to be replaced a year and a half ago, and I basically parked the car in the garage figuring out what I was going to do - either replace one head, both, rebuild engine or get another engine.

After finding an engine and getting the swap completed by a local independent shop, everything turned out great and the engine ran awesome, except the A/C. First lesson learned was to always replace the receiver drier whenever you open up an A/C system. I didn’t discuss evacuating the A/C system, installing a new receiver drier, and then recharging the system with the shop, but in hindsight that’s what needed to happen. The moisture from air will cause the system problems. Thus, if you ever need to replace one of the components in the A/C system, make sure you always plan on replacing the receiver drier too. After I picked up the car I got an estimate from an independent MB shop to replace the A/C compressor, receiver drier and expansion valve for over $1,600. They were going to use all new components and guarantee the repair for two years. So I scheduled an appointment the following week to do the repair. Then I read Mefferso’s thread. What a great write-up my friend. You got me inspired to do it based on your detailed procedures. I cancelled the appointment and decided to learn all I could about A/C repair to do the job myself.

Now about the repair. I tried to add all of information I learned using MB procedures and from the internet and also lessons learned during the process. Please don’t be intimidated based on the length of the write-up. It’s really not that complicated. I just tried to document everything from a first timer’s point of view. It is written for the DIYer who is good with tools and wants to learn all he can learn about doing the A/C system beforehand so it can be done with confidence and can be done right the first time! After doing the procedures in the post, I would rate the difficulty at a 2.5/5, with 5 being really difficult. I really don’t think it was that difficult, it was just not knowing what to expect that edged it to a 2.5 for me. The replacement of the parts are probably at a 2/5-2.5/5. Charging the system was a 3 for me initially without detailed instructions. But now having done it, I would rate it 2-2.5/5. It took me a day as I did some extra vacuuming and also wrote notes along the way. Sorry I didn’t take many pics!

These are the parts I ordered online. There are less expensive options on Ebay and other sites, but I chose to go with these based on quality, ease of ordering/obtaining and warranty.

Parts List:
-Denso 471-1594 compressor (new, no core charge and exactly like original).
MB part number: 0022305211
: Cost: $330. I paid an extra $60 for the 3yr warranty.

-Rein Expansion valve (same exact, and says Fujikoki on it, just like the original).
MB part number: 1648300084
FCPEuro.com, Cost: $76, Includes lifetime warranty.

-Behr Receiver Drier. (just like original and was an exact fit).
MB part number: 351335171
FCPEuro.com, Cost: $43 (sale price), Includes lifetime warranty.

-Santech MT2630 A/C System O-Ring and Gasket Kit, : $14
-TCW MT3012 PAG-46 oil. (Has 8oz), $14
-Robinair 10597 Dial Thermometer, $12
-Fox Run Brand 4oz Small measuring cup, : $6
-(Optional) Howard Leight Max-1 foam plugs (20 count), $5.50
-Ozeri Pronto Digital Scale, $15

Locally I purchased:
-Interdynamics - R-134a Dispensing Valve (Metal freon tap valve with 1/2” fitting for A/C yellow hose), O’Reily’s: $7
-Husky Precision Pick Set, Home Depot: $6
-3 cans IDQ R134a freon, Home Depot: $9/each
-(Optional) A/C Pro Universal UV Dye, O'reilly's: $9

Other optional items I used:
-3x5 note cards (I put the screws, rivets, etc. into a zip lock bag and labeled on note cards for organization and faster reassembly)
-cotton swabs (to add PAG oil to o-rings and inside of A/C part ports)
-small wooden blocks (used to push lines out of the way and pull wheel well liner back)
-plastic cup (to put PAG oil in to dip finger/cotton swabs in to moisten o-rings)

Tools I used:
safety glasses
nitrile gloves
Torx T-25 bit/screwdriver
Torx T-30 bit/screwdriver
Torx T-45 socket/bit (for drier bolt)
3/8” socket ratchet
10mm 3/8” socket
16mm 3/8” socket (to be used with E-14 socket to remove cross bar on top of engine)
17mm 3/8” socket (12 point) (to loosen serpentine belt)
3/8” universal joint socket
3/8” 12” long extension
10mm closed wrench ratchet
3/8” wrench sockets
3/8” E-12 metric socket (for compressor bolts to engine block)
3/8” E-14 metric socket (to remove cross bar on top of engine)
allen sockets (metric) (for expansion valve and A/C lines that connect to compressor)
torque wrench (you can rent one from Autozone in their tool rental program)
small flat head screwdriver
larger phillips screwdriver
regular needle nose pliers
long needle nose pliers
foam ear plugs (to plug high/low pressure ports of A/C system)
1/4” socket ratchet
1/4” 8” socket extension
10mm 1/4” socket
Pick set (to remove old o-rings)
small measuring cup (to measure PAG-46 compressor oil)
Thermometer (to measure interior air vent temp)

MB Specifications:
Freon: (as noted on engine sticker): 2.13lbs +/-.04lbs or 34.08oz +/-0.64oz of freon (0.97kg +/-0.01kg)
PAG-46 oil for compressor: 110mL

If you’re going to add freon yourself, items needed:
-3 cans of R-134a freon (12oz) - just plain freon, no added leak protection or dyes
-1 self-piercing metal can tap valve - I got the 1/2” male thread version based on my yellow hose.
-1 small scale that can measure ounces -I used the Ozeri Pronto Digital scale from Amazon: $15
Notes on Valve tap: When getting the self piercing metal can tap, make sure the male threaded stem from the tap valve will go into your yellow hose. Mine did because the yellow hose was a 1/2” female thread and the valve tap was a 1/2” male thread. Depending on your setup, make sure they will fit because sometimes hoses and/or valves may be 1/2” or 1/4”. I got the 1/2” one from O’Reily’s as it would fit the 1/2” yellow hose.
Notes on Scale. The reason why you need a scale is to measure out 10oz out of the last 12oz can. My system takes 2.13lbs +/-.04lbs or 34.08oz +/-0.64oz of freon (0.97kg +/-0.01kg), as noted on a sticker inside the engine compartment. So I planned on just adding 34oz even: 12oz from first can, 12oz from second can and 10oz from third can. Well, I wanted to see how well the scale was going to perform when having a can, metal tap valve and hose attached and how the scale would perform to measure out the last 10oz - because as the can dispenses, it will get lighter and potentially move around. I initially bought an inexpensive scale from Staples and it was terrible. Any slight movement and the numbers were erratic. So I ended up getting the Ozeri Pronto Digital scale from Amazon for $15. It had good reviews online, and I tested it before hand and it handled moving around of the can with tap and hose like a champ. It worked great counting down from approx. 20oz with freon can/tap/hose attached to 10oz during the actual refilling of the freon.

Autozone Tool Rental:
Tool rental at Autozone means you pay full price for the following items at checkout. They are used items but work good as long as you check them over as you are getting them from Autozone. I detail my experience below. Once you’re done with the tools, you have 90 days to return them for a full refund.
-A/C gauges and hoses.
-Vacuum pump.
-Torque wrench (I had one, but if you don’t have one you can also rent this tool. It’s about $100 to rent, but you will get your money back).
I think I spent about $300 on the Autozone A/C gauges and vacuum pump tools, and when I returned them the money was deposited back into my account within 2 days. Some lessons learned during the Autozone tool rental. After I rented the tools and when I initially hooked up the gauges and hoses to the high and low pressure sides to the car and vacuumed the system for 45 mins to make sure there wasn’t a current leak in the system, I was disappointed after I closed the valves at the gauges and turned off the vacuum and waited 45 mins (to make sure the system held a vacuum) to find out that my A/C system didn’t hold a vacuum. So I worried with having just done the engine change where could the leak be? Well, it turned out the green rubber o-rings in the Autozone hoses were mangled from the previous user tightening them down too tight and messing up the o-rings. I took the gauges/hoses back and exchanged them for a much better set. The hoses really are meant to only be tightened down by hand and let the o-rings do their job. After I got the new hoses, the system held the vacuum correctly. So I knew I was starting with a leak free system.
Note: If you’re system does not hold a vacuum at any of the steps along the way, I talk about doing some troubleshooting at the end.
To prepare for the job I took my car to a local A/C shop to evacuate the system. They charged me $69 to evacuate the system. Doing so was the environmentally right thing to do and it also gave me peace of mind knowing it was done right.

I. Expansion Valve Removal/Reinstallation:
I’m going to upload the WIS procedures for this. The procedures are set up for both GL/ML and various engine types, so there are some differences in the WIS pictures/procedures. These procedures below are for the GL450/X164. The GL450 is the 164.8 model with the M273 engine.

1. Open hood to it’s almost vertical position. There is a button on the driver’s side (towards bottom of hood raising mechanism) that you push to allow hood to continue to raise to it’s secondary/almost vertical position, and it will lock in place. You will need to push this button again later to bring hood to it’s lower position to close the hood.
2. Remove the cabin air intake cover. On passenger side of engine compartment. Push the two clips up to unclip. I used a flat head screwdriver. Then pull the cabin intake cover out. (Illustration in the attached document Strut_Tower_Brace)
3. Remove the strut tower brace (cross bar from left to right air strut). This is the bar on top of the engine towards the rear of the engine. This is necessary to remove the rear engine cover to get access to heat shields. Use 16mm socket and E14 metric sockets to take out the four bolts - two on each side (take care when removing the bolts to stay away from the air strut “air” lines). Also take note of how the bolts are inserted prior to taking them out (front to back or back to front). When reinstalling later these bolts get torqued to 50Nm (36.8ft-lbs). (Illustration in attached document Strut_Tower_Brace)
4. Remove the forward engine cover. To remove just pull up on the cover.
5. Remove the rear engine cover. Unclip the rear metal clip by pushing the clip towards rear of engine (it’s on top and towards rear of engine) gently pull up on the cover from the front and the entire cover will pull up. Take note of the clips on the underside of the rear cover and where they go on engine to reinstall later. I placed a plastic bag over the MAF sensor (metal mesh that goes into the intake manifold) to keep any debris from getting in.
6. Remove long rear rubber molding that goes left to right (that protects from the hood).
Note: At this point I ended up putting a big blanket on top of the forward part of the driver’s side of the engine to protect the components as I leaned my body on top of the blanket with my legs suspended by a small table in front of the car to do the following procedures. This made it a lot easier to get to the expansion valve once the heat panels were removed.
7. Remove three engine heat panels. These require 10mm socket. Take a pic of how they are mounted before taking them out as there is some overlap of two of the panels when reassembling. (Illustration in the attached document Air_Filter_Housing)
8. In Step 6 of the Expansion Valve WIS procedures, it states to remove the black plastic bolt (near the low pressure port) that's positioned vertically and connects the low pressure A/C line and another black line, but I found that this step to not be necessary on the GL (maybe necessary on the ML). (Illustration in the attached document Expansion_Valve_Replacement)
9. Now you’ve got access to the expansion valve that’s located in front of the driver’s side firewall.
10. Remove the 10mm nut from the expansion valve retaining plate that holds the high and low pressure lines into the expansion valve.
Note: The WIS procedures discuss using plugs to plug the various ports as you disassemble. I also wanted to take every precaution about any extended exposure to air or debris getting into any of the the ports leading to or behind the expansion valve as I don’t want to ever have to replace the evaporator! So before I proceeded I planned to use foam ear plugs and plug the high and low pressure lines as I took them off. To seal the various ports with the foam ear plugs, you can roll while pinching them with your fingers to compress the plug, then place in the various ports and it will expand sealing the ports from air and debris.
11. Take the retaining plate and pull it out along the hose and out of the way.
12. Before you remove the high and low pressure lines from expansion valve, I opened up the blue/low pressure line at the manifold gauge to remove the vacuum from the system. If not you could potentially vacuum debris into the low and high pressure lines at the expansion valve as you remove the lines as the system is currently under a vacuum - I know this may be overkill, but it was my first time and I only want to do this once!
13. Now remove the high and low pressure lines by gently pulling on them and plug them with the foam plugs, and push them out of the way. I ended up using a small wood block to keep them pushed out of the way to get access to the expansion valve.
14. Remove the expansion valve. Before I removed the expansion valve I got another pair of foam plugs ready to plug the high/low ports leading to the evaporator. I used a smaller allen wrench socket (forgot size) to remove the two screws that hold the expansion valve on.
15. With the expansion valve removed, I plugged the high/low ports that lead to the evaporator and removed the two o-rings at the port (that leads to evaporator) with a pick.
16. Install new o-rings on interior ports that lead to evaporator. Match up the o-rings with new o-rings from your kit and put some PAG oil on the new o-rings and install on the the internal low/high pressure ports (that leads to evaporator).
Note: Do not use a pick or screwdriver to install new o-rings, doing so could damage the new o-rings and could cause a leak in the future. I just used my fingers to put them on.
17. Install new expansion valve. I got a cotton swab with some PAG oil on it and swabbed some oil in the port area of the expansion valve before reinstalling it. Now remove the plugs and install the new expansion valve. I put a small amount of oil on the two screws to make them easier to go in and then tightened them evenly with an allen socket, so the expansion valve would seat evenly onto the new o-rings.
Note: when trying to get the two screws that hold the expansion valve started, I had to really push in on the expansion valve as the screws aren’t that long. Also, the two screws actually attach to an interior retaining plate behind the expansion valve. I used some needle nose piers on the exterior of the expansion valve and gently pushed the expansion valve in, while at the same time I used the 90 degree angled pick to pull out and position the interior retaining plate right next to the expansion valve. Doing this allowed me then use the allen socket with screw with my right hand (while holding the expansion valve in with my left hand with needle nose pliers) to get the screws initially started. After the two screws have been evenly screwed in, with the socket wrench, MB specs calls to torque the two screws to 8Nm (5.9 ft-lbs). If you don’t have a torque wrench, try to remember how tight the bolts were when removing them.
18. Remove/replace o-rings on high/low pressure lines. Now that the expansion valve is installed, use a pick to remove the old o-rings on the low/high pressure lines. Match them up to the o-rings in your kit and lubricate the new o-rings prior to putting them on the lines. Install new o-rings onto the low/high pressure lines.
Note: Do not use a pick or screwdriver to install new o-rings, doing so could damage the new o-rings and could cause a leak in the future. I just used my fingers to put them on.
19. Now install the high/low pressure lines into the expansion valve. I used a cotton swab and put some PAG oil in the port areas of the expansion valve and again on the new o-rings on the high/low lines, removed the ear plugs and pushed the lines into their respective ports.
20. Install exterior high/low line retaining plate - Place the high/low lines retaining plate back onto the lines and screw the 10mm nut back onto the plate. MB specs calls to torque this nut to only 5Nm (3.7 ft-lbs).
21. I then performed a vacuum check at this point where I vacuumed the system for 45 mins, waited 45 mins to make sure there wasn’t a leak. Expansion valve is done! I then proceeded to re-install the covers and other items removed in reverse order (Steps 7-1).

Notes on Reassembly:
-Rear engine cover: when reattaching rear engine cover, start with the rear part of the engine cover to seat over the MAF and ensure the rear clips go into place then seat the front part. You’ll know the rear part of the cover is installed correctly when you see the rear metal clip and it can easily be pulled forward to it’s detent. If the metal clip cannot be easily moved forward, you don’t have the rear engine cover properly seated in the rear.
-Reinstalling Strut Tower Brace (cross bar): you reinstall by positioning the bar initially at the right then sliding it left into place. Make sure the rubber grommet on the passenger side is lined up with the engine heat shield (so the long rubber mount that goes on top from left to right will properly seal onto it).

II. A/C Compressor Removal/Reinstallation:
I’m going to upload the WIS procedure for replacing the A/C compressor. At this point I ended up removing the front bumper cover and the driver’s side front wheel and wheel well liner. WIS calls to remove the front wheel in the 164.8 model (which is the GL450). This is key because doing so gives you access through the wheel well to the top bolt of the compressor, the electrical connection for the compressor and the inlet/outlet ports of the compressor. Removing the front bumper cover is also required to give you access to the drier.

A. Remove front bumper cover:
Note: I used ziplock bags and note cards to label and organize all of the bolts, rivets and screws. This made reassembly much easier.
1. Remove the engine plastic shield under the engine. All of the bolts are 10mm. If your car has it, remove the forward chrome skid plate as well using a T-30 torx bit.
2. Remove driver’s side front wheel. Place blocks behind the rear wheels to prevent the car from rolling backwards. And place jack stands under car for safety.
3. Remove forward section of driver’s side wheel well liner. Start on the driver’s side by removing the three plastic rivets on the forward part of the wheel well liner. A small screwdriver can be used to gently pull up the center pin portion approx. 1cm, then use the screwdriver to pry up the main part of the plastic rivet. Once it’s up a little, I used a needle nose to pull it out.
4. Remove two 10mm nuts holding wheel well liner in (one is on the inside top of wheel and one is closer to axle) and remove wheel well liner.
5. Remove one T-25 torx screw on the inner top portion of the wheel well lip that attaches the top of the bumper cover to the fender (this is just above the top of the three rivets you just removed).
6. Now looking forward inside the bumper cover, there is a gear looking black plastic piece with a 10mm bolt. Loosen that 10mm bolt, but don’t remove it. I used a 10mm closed wrench/ratchet because it was easier than using a socket wrench in the tight space. A 1/4” drive socket with 10mm socket will also work.
7. Now go to the passenger side wheel well. It’s not necessary to remove the entire forward portion of the passenger wheel well liner.
8. Remove the three wheel well liner rivets like you did on the driver’s side in step 3.
9. Remove the T-25 screw as you did in step 5.
10. Now pull the wheel well liner back (I used a small block to keep the liner pulled back, towards the tire) to get access to the 10mm bolt on the black plastic gear looking mechanism that you loosened in step 6. Loosen the 10mm bolt but don’t remove it. Again, I used the 10mm closed wrench/ratchet.
11. With the hood open, remove the two top 10mm bolts that the bumper cover attaches to on the top forward part of the engine. After the bolts are removed you will pull these two top parts up about 1/2 inch and over the “lip” and now the entire bumper cover is ready to be removed.
12. Remove bumper cover. Get a blanket ready to put the bumper cover on as it will want to lay face down after removing it. Get a friend to help on either side of the bumper cover to slowly pull the bumper cover off. It requires some force but not too much force and be cautious when you finally get it free because there are two electrical connections for the lower lights. I had placed the blanket directly below the bumper cover so once we got it off, it was laying on the blanket as I disconnected the two electrical connections. Be careful when disconnecting the electrical connections to not break the latch mechanism - then move the bumper cover out of the way.

B. Remove/Install A/C Compressor
13. First remove the serpentine belt. I just used a 12-point 17mm socket with my socket wrench to move the belt tensioner counter clockwise to loosen the serpentine belt. Note: for those who have never loosened the serpentine belt (I hadn’t), the 17mm bolt is just to the lower left of the actual pulley (as looking at the pulley from the front of the car). With the serpentine belt off the tensioner, I took the loosened belt off the compressor.
Note: Before I removed the low/high A/C lines at the compressor, with the yellow hose still attached to the vacuum, I opened the blue/low pressure valve at the manifold gauge, to slowly remove the vacuum from the system (the A/C compressor area was dirty and I didn’t want to “vacuum” any debris into the system as I removed the A/C lines).
14. Remove high/low compressor lines. Now through the driver’s front wheel well use an allen wrench socket (you can size the allen socket size from your new compressor plugs) on a 12” socket extension to remove the high/low pressure lines. Plug them with foam plugs and push then out of the way.
15. Remove electrical connection. Looking through the driver’s side front wheel well, remove the electrical connection on the existing compressor. You can see on the new compressor the lip part that the electrical connection latches onto. I used a long flathead screwdriver to carefully lift up on the latch then used a long needle nose pliers to carefully pull the electrical connection out of the compressor. Once this electrical connection was detached, I put some tape on the connection and taped it out of the way.
16. Remove A/C compressor star headed bolts. Using a metric E12 socket, loosen the two bottom star headed bolts from underneath the car. To loosen the top bolt I used a universal joint socket and 12” socket extension to loosen the top compressor bolt. These bolts weren’t difficult to remove as my compressor had recently been removed and replaced during the engine swap. Mefferso said he had to bang on some of the bolts to get them to come free. It may require a breaker bar to loosen.
Note: Make sure the E12 socket is fully seated onto the bolts before you try to turn them counter clockwise to remove (I almost stripped the top star bolt because I initially didn’t have the socket fully seated). Once they were loose I was able to loosen the bolts with my hand. I took the top bolt out first then removed the bottom bolts from underneath the car. Be sure to hold the compressor up with one hand when taking out the last bolt as the compressor weights 12lbs. Now work the compressor down past the power steering lines and remove.
17. Add PAG-46 compressor oil to new A/C compressor. The purpose of the PAG-46 compressor oil is to lubricate the compressor during operation. My new compressor didn’t have any oil in it. MB specs call for 110 mL of PAG-46 compressor oil. I measured the oil in a measuring cup, removed one of the ports, poured the oil into the larger port of the compressor, replaced the port cap then turned the pulley 10 times. Note: you can add oil to either port. Also, when adding the PAG oil, you may need to turn the pulley a few times to work the oil into the compressor to be able to add all of the 110mL of oil. The Denso directions say to turn the compressor pulley 10 times to work the oil in after adding oil. With the cap replaced on the compressor you’re now ready to reinstall the compressor.
18. Install new compressor. I did it like this - I put a little bit of oil on the mounting bolts to make it easier to hand tighten the bolts while reinstalling. Work the compressor up from underneath the car and get one of the two bottom star mounting bolts started to get the compressor attached to the block. Get the other lower bolt started; now you’re ready to get the top bolt in. Working from inside the driver’s front wheel well, I was able to hand tighten the top bolt in most of the way using the universal socket with E12 socket attached. Then I attached the 12” extension and used the ratchet to tighten further. I tightened the two lower bolts with ratchet and when all three bolts were evenly tightened to the block, I torqued the three bolts to the MB spec of 20Nm (14.8ft-lbs).
19. Attach electrical connection. I used a long needle nose pliers to slide the male electrical connection into the new compressor electrical sleeve. You could also just use your hand to push the electrical connection into the compressor electrical sleeve. Carefully push it in far enough to ensure the latch latches to over the locking lip on the compressor side connector. I used a long flathead screwdriver to make sure the latch was pushed down over the latch lip. Now you're ready to install the high/low pressure lines.
20. Remove old/install new o-rings to low/high pressure lines. I used a pick to remove the old o-rings. Match them to the o-rings in your new o-ring set. Lubricate the new o-rings with PAG oil and install on the low/high pressure lines. I used my left hand through the wheel well opening to put the new o-rings on.
Note: Do not use a pick or screwdriver to install new o-rings, doing so could damage the new o-rings and could cause a leak in the future. I just used my fingers to put them on.
21. Install low/high pressure lines into compressor. Remove the low/high pressure caps on the compressor with an allen socket. I put some PAG oil on a cotton swab and swabbed the low/high pressure ports with some oil, removed the foam plugs from the low/high pressure lines then placed the lines into the compressor ports. Use an allen socket with 12” extension to tighten the low/high pressure A/C lines bolts to the compressor. MB specs calls for the A/C line bolts to compressor to also be torqued to 20Nm (14.8ft-lbs). The compressor is now installed!
22. Reinstall serpentine belt. Under the car with the belt loose, I put the belt over the new compressor pulley. Then from the top of engine with a 17mm socket, I moved the belt tensioner counter clockwise to loosen the tensioner and then reinstalled the belt over the tensioner pulley. Then release tension going clockwise to allow belt to tighten. Be sure the belt is lined up straight on both the tensioner pulley and the compressor pulley before releasing the tension on the belt. Now the belt is done!

III. Receiver Drier Removal/Reinstallation:
Note: MB WIS procedures calls the receiver drier a “fluid reservoir” in their instructions.
23. Remove retaining plate holding the two small A/C lines into drier. Start by removing the single bolt (T-45 Torx) holding the retaining plate with an T-45 wrench socket. You’ll need to pull the plastic guard out of the way to get the socket to reach the bolt. Take the bolt all the way out.
24. Remove two receiver drier tab bolts. Using a 10mm socket remove the two tab mounting bolts that under and under the driver and hold the drier onto the frame.
25. Now, holding the drier lines steady with your right hand, pull the drier to the left with your left hand to remove the lines from the drier.
26. I plugged the two lines with foam plugs while I worked on new drier.
27. Take the two mounting tabs from the old drier and install onto new drier. I used a flathead screwdriver to lift up on the locking mechanism of the tab to remove the mounting tabs, put onto the new drier and closed the locking mechanism (by pushing down with a screwdriver on the locking mechanism) so the mounting tab would stay in place.
28. Add PAG-46 oil to Receiver Drier. Measure 1oz of PAG oil into a cup. Take one of the plastic caps off new drier and pour 1oz of PAG oil into the new drier. While I didn’t see the MB procedures specifically call to do this, adding about 1oz of oil to a new drier seems to be the consensus of many A/C professionals when replacing a drier.
29. Replace plastic cap on drier. Replace the plastic cap on the drier after adding the PAG oil to the drier. This will help prevent air from getting into the new drier.
Note: MB procedures state to limit the exposure of the drier to air to 20 minutes to prevent excess air from contaminating the new drier.
30. Remove/install new o-rings onto the lines. Remove the old o-rings with a pick. Match them up to o-rings in your kit and lubricate the new o-rings with PAG oil and put them on the lines.
Note: Do not use a pick or screwdriver to install new o-rings, doing so could damage the new o-rings and could cause a leak in the future. I just used my fingers to put them on.
31. Install new drier. I swabbed the line ports on the new drier with a some PAG oil using a cotton swab. Now place the drier just to the left of the the A/C lines. Remove the ear plugs from the lines and remove the plastic caps from the drier. Then slide the drier to the right lining up the lines into the ports. Push the lines into ports.
32. Reinstall two mounting bolts into the two mounting tabs to secure the drier.
33. With the drier secure, you’re ready to reinstall the retaining plate that secures the two lines to the drier. Use the T-45 socket again. MB specs. calls to tighten this T-45 bolt to 8Nm (5.9ft-lbs). Now the drier is installed!

At this point while the car was still apart, I did a vacuum check (1 hour vacuum followed by 1 hour waiting to make sure it held a vacuum). The vacuum check was good. If you’re going to bring the car to a shop and have them do a vacuum and charge the system with freon, now is the time to reassemble the car in the reverse order. I decided to charge the system myself. I will go through those procedures then some notes on reassembly.

IV. Recharging A/C System with New Freon:
I found the youtube videos by Chrisfix and Erikthecarguy the most helpful on understanding the process of charging the A/C system with freon here:
Note: Now is a good time to make sure you’re wearing safety glasses and gloves to protect yourself during the following procedures.
Note: If you have a check engine light following installation of any of the A/C components, you likely need to get the check engine light cleared before you can try to recharge the system because the compressor may not turn on and you will not be able to charge the system with freon without the compressor turning on. An OBDII scanner can help to clear a check engine light.
1. Connect the A/C hoses. First remove plastic port covers on the high and low pressure ports. The low pressure port is easy to see, located on the top side of engine on the driver’s side. The high pressure port is a little hidden and is about 6 inches down in front of the condenser, on the driver’s side. Ensure the red and blue valves are closed at the manifold - at the gauges. My A/C hoses/gauges had the manifold valves turn clockwise to close and counterclockwise to open. Attach A/C blue/low and red/high quick connects to the low/high pressure ports on the car. The hoses are designed where the low pressure line can only connect to the low pressure port due to the difference sizes of ports on the car. So you can’t mess it up. Some connects are quick connects that basically pull back on the connector and place on the valve. Others are similarly placed on the valve and then opened up by turning the valve.
Note: Be careful if you have the type of hose connection that has the valve you open by turning the handle at the port -only open the valve enough to open the Schrader valve i.e. don’t “crank” it open or you could possibly bend/break the Schrader valve (looks like a large tire valve). At the ports, my connections turned clockwise to open and counterclockwise to close (opposite the manifold valves at the gauge). At this point with the blue/red valves closed at the manifold/gauge, open the blue/red quick connections at the ports.
2. Connect the yellow hose to the vacuum pump. Though the yellow hose seems like the same on both ends, make sure you attach the “open hole” end to the vacuum pump and attach the valve end to the gauge. The end that should be attached to the manifold gauge looks similar to the inside of the red/blue line hoses that are attached to the manifold gauge.
Note: if the yellow hose is backwards, it will pull a vacuum but the freon will not go in later when you get to the stage of charging the system with freon.
Note: The purpose of vacuuming the A/C system is to remove moisture from the air in the system. Vacuuming the system is critical and the A/C repair will be pointless if you do not take careful steps to follow the order of vacuuming properly. Essentially, vacuuming the system lowers the pressure of the system one atmosphere and “boils” off the moisture of the air in the system. Any moisture in the system will cause parts within the A/C system to eventually corrode/fail over time. Vacuuming the system also allows you to test the system for any leaks. If the system can hold a vacuum then you know there aren’t any leaks in the system. Also, vacuuming the A/C system will only remove air and moisture and any excess freon, but it will not remove any of the PAG oil that is already in the system. Also, by having the yellow hose in the correct direction, PAG oil can also be added to the system via the “open hole” end or end attached to the vacuum pump if you didn’t add the PAG oil to the compressor and/or drier during installation. More on the explanation of this later in step 7.
3. With the yellow hose attached to the vacuum pump and the valves closed at the manifold/gauge, turn on the vacuum pump.
4. Then open the blue/red valves at the manifold/gauges. You will hear the vacuum compressor start to work harder. And the vacuum gauges will start to go negative on their respective pressure gauges. You will also start to see a small amount of steam come out of the exhaust fan of the vacuum pump. This is moisture in the air being “boiled” out. You’re looking for the low pressure gauge to get to 29-30 inches of vacuum. It seems like most professionals vacuum the system for 45min-1hr. After 45min-1hr, close the blue/red lines at the manifold/gauge, then turn off vacuum pump.
5. Now you’re going to wait 45mins-1hr to ensure your car’s A/C system doesn’t have any leaks. When you return you want to make sure the vacuum on the gauges hasn’t moved at all -should still exactly be at the 29-30 inches vacuum on the low/blue gauge and the same negative value on the high/red gauge. I ended up doing another 1 hr vacuum and another 1 hr wait just to be sure it was perfect.
6. Charge the system. With the system tested and confirmed for no leaks with the vacuum test, you’re now ready to charge the system with freon.
Note: A quick check of connections at this point: the blue/red connectors are open at the ports, the blue/red valves are closed at the manifold/gauges.
7. (Optional) Add UV dye to the system. Remove the yellow hose from the vacuum pump. Remember, the vacuum pump side of the yellow hose should be the “open hole” side of the yellow line. Now is a good time to add A/C UV dye. I poured about 1.5 capfuls of the UV dye directly into the yellow line after I removed the yellow line from the vacuum. It’s not necessary to add any more dye. Also, if you forgot to add any PAG oil to the compressor and/or drier during installation, you can add/pour PAG oil directly into the yellow line via the yellow hose “open hole” side that was connected to the vacuum pump just like adding the UV dye.
8. Attach metal tap to yellow hose. You’re now going to attach the metal tap to the yellow hose end. I had the can tap handle turned counter clockwise to not puncture the first freon can while screwing it on onto the tap female port.
Note: the metal tap handle is kind of flimsy, so you shouldn’t “crank” open or closed the handle, just open and close the handle enough to the pierce the can and/or open the tap valve to the yellow line.
9. Attach the first freon can to the metal tap. Screw the freon can onto the metal tap. With the can snug into the can tap port, rotate the can tap handle clockwise to puncture the freon can. With the freon can punctured, now, you can turn the tap handle counter clockwise to open up the can to the yellow line. At this point you will hear some of the freon go into the yellow line.
10. Purge the air from the yellow line. Be sure you’ve got your safety goggles and gloves on now. So at this point you’ve got a vacuum in the A/C system in the car, the blue/red valves closed at the manifold/gauges, and the tap with the first can of freon attached to the yellow line with the freon can tapped and the metal tap handle fully open. Now you need to purge the air that was in the yellow line as you added UV dye (in step 7) and hooked up the metal can tap and freon (step 8). To purge the air you will use a larger phillips screwdriver to press on the valve at the top of the yellow line (just below the gauge) and be sure to point the valve away from you. I used 2-3 short (approx. 1/2 second) taps. The first one had some air come out and the next three had some freon come out in a spray. Now the yellow line is purged of air and the freon is ready to be put into the car.
Important: The following steps need to be followed in the correct order to properly recharge the A/C system.
11. Start the car.
12. Insert the thermometer into the air vent just above the A/C controls to measure the temperature of the air after you add freon.
13. Turn the air conditioning on. My starting temp was a balmy 96 degrees F.
14. Set temperature selectors to the coldest temperature with the fan on low.
Note: I put the scale on a small table in front of the car to be stable and put the freon can with tap and hose attached onto the scale. I decided to do the 10oz can first because the third can will take longer to dispense, and I didn't want to worry about watching the scale for a longer period of time. Also, if I messed up the first can and went over 10oz, I could empty the first can and do 10oz of the second can instead. So, the first can weighed 19.8oz, so I needed to bring the scale to 9.8oz to ensure that only 10oz of freon was drawn into the system from the first can. These weight values of can, metal tap and hose will vary based on your setup.
Caution: When adding freon to the system, make sure you only open the BLUE/LOW pressure line at the manifold. Never add freon to the red/high side.
Caution: Also make sure you open the BLUE/LOW pressure gauge very slowly initially to allow the freon to be sucked into the system, noting the pressure on the gauge. Opening the valve too quickly could damage the expansion valve or cause it to ice up not allowing the freon to enter and circulate into the system.
15. Discharge freon into the A/C system. Put some gloves on as the freon can will get cold as you add freon to the system. With the first can on the scale weighing approx. 20oz (19.8oz in my case), slowly start to open the BLUE/LOW pressure line at the manifold/gauge. You will see freon starting to go into the system through the site glass and you will see the blue/low pressure gauge start to increase. Once there is enough freon in the system the system the compressor will kick on and the pressure in the blue/low pressure gauge will decrease to about 10-20psi as freon is sucked into the system. Once the compressor kicks on and the pressure drops, you can start to open the blue/low manifold valve more to allow the freon to flow into the system more. I turned the can sideways periodically then put it back on the scale. It took about 4 minutes or so to have 10oz go into the system. As you are approaching the 10oz, I put my hand on the blue/low pressure manifold/gauge handle and started to close it, then as the scale hit 10oz (9.8oz in my case), I closed the blue/low pressure valve. Now with the blue/low pressure manifold/gauge handle closed and the metal tap valve open you’re ready to remove the first can from the metal tap.
16. Remove freon can containing the 2oz of freon in it from the metal tap. Slowly and pointing the can away from you, unscrew the freon can from the metal tap. As you do so you will hear/see some of the freon gas escape as you take it off. Unfortunately, I don’t know a better way to DIY than this.
17. Attach the second freon can to the metal tap. Screw the second freon can onto the metal tap. With the can snug into the can tap port, rotate the can tap handle clockwise to puncture the freon can. With the freon can punctured, now, you can turn the tap handle counter clockwise to open up the tap valve to the yellow line. At this point you will hear some of the freon go into the yellow line again.
Note: Now the yellow line has freon in it BUT it also has some ambient air in the yellow hose, so you’re going to have to purge the air as you did in step 10.
18. Purge the yellow hose of ambient air. To purge the air from the yellow hose you’ll do the same procedure as was done in step 10: Use a larger phillips screwdriver to press on the valve at the top of the yellow line (just below the gauge) and be sure to point the valve away from you. I used 2-3 short (approx. 1/2 second) taps. The first one had some air come out and the next two had some freon come out in a spray. Now the yellow line is purged of air and the freon is ready to be put into the car.
19. Discharge second can of freon into A/C system. Now with the yellow hose charged with freon, slowly open up the blue/low pressure valve at the manifold and watch the pressure gauge as the freon enters the system. You want to slowly add the freon to the low system pressure noting the pressure gauge to ensure it doesn’t get too high. The A/C line near the low pressure port will start to sweat and the temperature in the car will start to lower. You may need to turn the can sideways to help the freon get out. Also, it’s going to take longer for the freon to discharge from the can and get sucked into the system. Maybe about 6 minutes or so. Toward the very end I turned the can upside down to get every bit I could out of the can until it’s completely depleted.
20. Now close the blue/low pressure valve at the manifold gauge. Doing this ensures that no freon can escape from the blue/low pressure line.
21. Remove second can from metal tap. While twisting the can off the metal tap a very minor amount of gas that was in yellow line will escape as you twist the can off.
22. Now you’re ready to install the third can of freon. Screw the third can onto the metal tap. With the can snug into the can tap port, rotate the can tap handle clockwise to puncture the freon can. With the freon can punctured, now, you can turn the tap handle counter clockwise to open up the tap valve to the yellow line. At this point you will again hear some of the freon go into the yellow line. At this point you have the third can twisted onto the metal tap, and the tap valve is open and freon is in the yellow hose.
Note: Now the yellow line has freon in it BUT it also has some ambient air in the yellow hose, so you’re going to have to purge the air as you did in step 10.
23. Purge the yellow hose of ambient air. To purge the air from the yellow hose you’ll do the same procedure as was done in step 10: Use a larger phillips screwdriver to press on the valve at the top of the yellow line (just below the gauge) and be sure to point the valve away from you. I used 2-3 short (approx. 1/2 second) taps. The first one had some air come out and the next two had some freon come out in a spray. Now the yellow line is purged of air and the freon is ready to be put into the car.
23. Now discharge the third can into A/C system. Slowly open the low/blue valve at the manifold. The last remaining 12oz will take some time to be discharged into A/C system. Every so often I turned the can sideways and back up. Depending on your ambient temperature conditions, it may take up to 10 mins to discharge the final can. Continue until the third can has been completely emptied.
24. Close the blue/low pressure line at the manifold/gauge. Once the third can is completely emptied, now close the blue/low pressure line at the manifold/gauge. You have now stopped any freon or air from going into the A/C system.
25. Now close the metal tap valve by turning it clockwise.
26. Now a connections check: the blue/low pressure line at the manifold/gauge is closed, the red/high pressure line at the manifold/gauge is closed. The metal tap valve is closed.
27. Remove third freon can from metal tap. Twist the third can off the metal tap. A very minor amount of gas will escape as you twist the can off. Now the A/C system is completely charged!
Note: I then went inside the car to check the temperature and was very happy to see the thermometer at 42 degrees F. Success!
28. Remove A/C hoses from low/high pressure ports. At the low/blue pressure port, remove the low/blue quick connection. With my hoses I turned the port connection counter clockwise to close the valve then removed the connection. At the high/red pressure port, remove the high/red quick connection. Again I turned the connection counter clockwise to close the high/red connection then removed the connection.
29. Replace plastic caps on low/high pressure ports. A/C system repair is complete!
30. Reassemble car in the reverse order.
31. Congrats! You've just created a meat locker in your GL! Crack open a beer or two!

Notes on Reassembly:
-Reinstalling bumper: you’re going to need help getting the bumper back on the car. Reattach the two electrical connections and then slide bumper back into place just below the left and right side fenders. There is an internal body mount plate that attaches to both the forward part of the fender and the bumper cover. It has a vertical pin that will slide evenly into a groove in the front of both the fender and bumper cover. Using a flashlight, you want to ensure that the vertical mounting plate is properly lined up with the forward part of the top portion of car and with the bumper as you slide it in. Once it’s lined up, you can then reinstall the T-25 bolt and screw it in. Also, make sure the fastener that the T-25 screw goes into is securely attached and centered on the hole. My driver’s side went in easily, but my passenger side needed some work to get the fastener on the plate lined back up and to get the vertical pin lined up properly so the bumper is properly aligned with the fender. Now you can reach in with the 10mm closed ratchet wrench and tighten the 10mm bolt on the gear looking mechanism that you loosened in step 6 of bumper procedures.
-Reinstalling wheel well liner: an easy way to reinstall the plastic rivets is to hold the rivet with a needle nose pliers by the center pin (with the center pin only partially inserted into rivet), using the pliers sideways and the pin in the jaws of the pliers, push the rivet back into the hole to hold the wheel liner. With the rivet installed, then push the pin in. If you try to reinstall the rivet with the pin fully inserted into the rivet, it will likely break the rivet.

Final thoughts:
I will post some ideas on troubleshooting in the next post.
-Flushing the system. This would be a good idea if your compressor died during operation. In this case it’s likely metal particles of the compressor came apart during the failure and could have gone into the system. There are various YouTube videos on how to flush the system and the lines. I didn’t flush my system as I didn’t believe my compressor had failed following my engine swap. I believe the week long process of swapping the engine and having the drier exposed to air caused the drier to have too much moisture. And that the compressor due to it’s age and sitting for so long was likely due for a replacement.
-Not replacing condenser. I opted to not replace the condenser at this time. Had I not achieved a low temperature in the 40-50 deg. F range (mine achieved 42 deg. F), I planned to first clean the condenser with a condenser cleaner - Nu-Calgon 4171-75 Evap Foam No Rinse Evaporator Coil Cleaner. If that didn’t work, then I planned to evacuate the system again at a shop and replace the condenser. If/when my system starts to not cool as efficiently, I will likely first clean the condenser and/or replace the condenser.

I look forward to anyone having their thoughts and comments going forward. Thanks again to all of the members who have contributed to this site. Your experiences and technical knowledge gave me the confidence to tackle a project I likely would have never done myself.

JamesMitchell

Troubleshooting:
1. What if your A/C system doesn’t hold a vacuum to start with? My plan if my system didn’t hold a vacuum was to order the following part from Amazon: LotFancy Refrigerant Freon Leak Detector. It’s only $23 and has really good reviews (note: if you get this product, make sure you put in 4 AAA batteries - 2 on the top and 2 on the bottom). Either way, you’re going to have to go through the process of either using an electronic freon leak detector or adding UV dye to the system to try to find the leak. Also, you’re going to need to get the A/C compressor functioning in order to spread the freon and dye throughout the system. If your system was leaking compressor oil, I would also consider adding some compressor oil. Adding the compressor oil will lubricate the compressor and may also help identify a wet/oil spot with UV dye while troubleshooting. Here are a few cases to consider:
Case 1. Your A/C compressor is working. If you’re compressor is functioning then using an electronic leak detector and/or the UV dye and adding freon to spread throughout the system can help to identify the leak. You can buy some UV glasses and UV flashlight kit locally or online to look for leaking UV dye and/or compressor oil.
Case 2. Your A/C compressor is not working. I would first want to check to make sure power is getting to the A/C compressor. This can be done by getting to the electrical contact at the compressor and getting a volt meter to test it. If it has electrical power, next I would want to make sure the the A/C system has the appropriate amount of freon in it. The A/C compressor will only turn on when the appropriate amount of freon is detected. I would consider having the freon evacuated at a proper facility and then pull a vacuum on the system and then try adding freon to get the compressor to work. If the A/C system has too low of freon or too high an amount of freon, the compressor will not turn on. If your compressor has electrical power and you’re still not able to get the compressor to turn on, then you’re likely going to have to replace the A/C compressor and drier in order to get it working. Then perform a vacuum. It may end up being that your system initially holds a vacuum but slowly leaks. This will work to help identify the leak with an electronic device and/or adding the UV dye and adding some freon to hopefully get the compressor to spread the freon and UV dye throughout the system to identify the A/C leak. The initial vacuum on the system will help draw the freon into the system and with the added freon the compressor will now start to function to draw more freon into the system. With my limited experience I would probably only plan on adding one can of freon to help find the UV leak. Once found, you’re going to have to evacuate the system again in order to repair where the leak is, then go through the vacuum and recharge process as detailed above.
2. What if your temperature doesn’t get to a cold temperature? I was worried about this too. Whether you had a shop vacuum and charge your A/C system or you did it yourself, there is a chance your A/C temperature may not achieve a very cold i.e. 40-50 degrees F. temperature. The likely culprit is your condenser. For me, if I didn’t achieve 40-50 degrees F., I planned on getting a condenser cleaner and giving it a complete cleaning. I know for sure my condenser has never been cleaned and though it may not look that bad visually, there is a good chance it’s clogged and a good cleaning could help your A/C system to run more efficiently and, thus achieve the 40-50 degrees F. you’re striving for. If, after I cleaned the condenser and the temperature still wasn’t in the 40-50 degrees F. range, I planned on evacuating my system again and replacing my condenser.
3. What if you don’t get a cold temperature when the car is stopped at idle, but the temperature gets colder as you drive it? Again, this could be a condenser that is starting to fail. Also, there is the cooling fan (right behind the condenser) that could possibly be starting to fail. I would use an OBDII scanner and see if the cooling fan is possibly giving a fault code. If it is, the cooling fan will likely need to be replaced.

Common leaking areas:
1. Anywhere there are o-rings in the system. I would check the connections (o-rings) at the compressor, the condenser, the receiver drier and the expansion valve first.
2. Also, the Schrader valve itself could be leaking. If this is the case there are apparently two options: 1. If it’s the low pressure port, they actually make a Schrader valve repair tool that allows you to replace the faulty Schrader valve without having to evacuate the system. The tool is called the Mastercool 81490 - Valve Core Remover/Installer. There is a helpful video on YouTube that shows how to use it here: starting at time 4:34. Now if it’s the high side, it looks like you will likely have to remove some of the front of the car because of its position in front of the condenser. 2. The other option is to get a new or used OEM line to replace the line assembly with the Schrader valve integrated into it. Do a visual inspection along the connection ports at the condenser at the inlet/outlet of the condenser. It may be that the o-rings are leaking. And if that’s the case you can replace the o-rings as detailed above. However, if the condenser is leaking and/or the inlet/outlet pipes themselves have damage, you will need to replace the entire condenser. I opted not to replace my condenser at this time, but may do so in the future if the quality of cooling in my system deteriorates over time.
3. At the connection points of the A/C lines throughout the system. The MB WIS diagrams or even websites like mboemparts.com has some good detail sketches of the A/C system and parts that can help detail the various lines and connections. Each of these connections points also have o-rings and are a possible source of a leak. If leaking, remember to replace the o-ring and lube the new o-rings with PAG oil before replacing.
4. Along the A/C lines to the rear A/C system. I’ve read about some members having technicians find leaks in the A/C line leading to the rear A/C system. OEM replacements of these lines are very expensive and labor intensive. There are some very helpful workaround solutions with in-line repair kits with either metal or rubber hoses to splice-in a repair. The following video looks like a good solution to fixing a line leak: Also, there are companies that specialize in splicing in repairs like agscompany.com with the Splice-Lok and other products.
5. Leak at the evaporator drain. If there is UV fluid in the water that’s coming out, you likely have a leak in your evaporator. I would love to have anyone who has done this repair to post their experience. This seems like a major repair. I would consider adding a stop leak product to see if the leak could be stopped as a temporary solution. I’ve read many posts and have seen some YouTube videos of folks who have had success with this. Ideally, you want to keep your A/C system as pure as you can with only R-134a refrigerant and a small amount of dye. Some folks have said adding various products of stop leak may eventually harm the compressor. I would consider adding a product like stop leak and perhaps after a short time, evacuate the system and then recharge.

Auldphart

I know I'm late to the party, but thanks JamesMitchell for this incredibly detailed post. Well done. I currently own 4 BMWs and have had a few more in the past and have done just about everything from head gaskets and clutch replacements to repairing subframe cracks. I always found a lot of resources on the various forums to give me extra insight before I tackle a job. Since we bought the GL450, I have found that there is not a whole lot of information out there from people who like to turn a wrench. I'm guessing that a majority of people who drive these cars are not inclined to repair them.

I split the job across three evenings and got everything buttoned up last night and I'm blowing beautiful 41-degree air now. Thanks for taking the time to document the job while doing it.

Iceytys

Old compressor

New Denso compressor from Amazon

Feeling great blowing 40 degrees


Using this thread did the compressor job myself in about 4 hours.....pretty easy job. Think I paid $338 for the compressor and another $250 on misc parts and freon evac and recharge. Much cheaper than the over $2K to replace the compressor and driver.


Thanks all

8AL8

james, thanks for detail write up....I went to your amazon link for AC compressor, its said not comparable for 2010 GL550 or GL450

cztexas

Hi, James, thank you so much for the details. I do have a question, why you fill 110 ml oil instead of 20ml for replacing the compressor? I have already checked and added it to 110 ml but when I searching, I found, 110 ml seems like the whole system oil, since I only change compressor plus dryer, should I just add 20 ml for compressor and 10 ml for dyer?

JamesMitchell

Hello. The answer is 110ml of PAG 46 oil for replacing the A/C compressor and an additional 10ML for replacing the fluid reservoir (dryer) -so a total of 120mL. Scroll down in the attached document and you will see the value of 110mL if replacing the A/C compressor and 10mL for replacing the fluid reservoir (dryer). These values are from the Mercedes workshop manual (WIS). Don't listen to what people "think" should be added. These values are from the manual. Btw, my system is still blowing freezing cold air in hot August Houston heat. Good luck!

cztexas

Thank you for your quick response. I really appreciate. By the way, I lived in Texas also. I have wait for so long to replace my compressor. First I thought it was the Solenoid Valve, but no luck. My other parts just arrived yesterday. Start to work on it now.
I checked the document from WIS, and certainly this is the one we should check all the time. But this is also the reason why I have concerns about the oil capacity. To my understanding, X164 take 110 ml oil in the system, which is the "Refrigerant compressor filling quantity" in your document. If my system was flushed completely, I will use this number. But since I only want to replace compressor plus dryer without flushing, I think the number should be the one "Additional oil filling quantity after replacing refrigerant compressor" (20ml) + "Additional oil filling quantity after replacing fluid reservoir" (10 ml). Since usually compressor only hold part of the oil in the system, and oil will be traveled to evaporator, condenser, dryer, etc. That's why WIS document listed different number for each part. Jus my thoughts. Not sure about it.

JamesMitchell

Hello. My writeup above was intended for an owner to repair the A/C system in their car without having to take it to an Independent shop or the dealership. Disclaimer: this is about what I learned about the A/C system and how I went about repairing it. The procedures and info written here are for informational purposes only. It's long and detailed, but I wrote it that way for a novice person to print and work with to help them achieve a repaired A/C system without taking it to a shop. With that said, the best way I interpreted the WIS or workshop procedures was to add 110mL of PAG 46 fluid to the system for a replaced compressor and an additional 10mL of PAG 46 fluid to the system for also replacing the drier. Whether you choose to add only 20mL to the system for the compressor and 10mL for the drier is up to you. I've provided the WIS instructions, but do with them as you wish. Best of luck to you on the repair.

cztexas

Thank you, James. Again, I really appreciate what you have put together. Yes, very long and detailed, and I kept learning from it. In fact, this is the best and most detailed procedures I have saw. I have touched other stuff, but never AC system before. This will my first time to replace the compressor. Your detailed procedures make me more confident to do this. Thanks a lot!

BENZ TRIPLET

Maybe I am not using the correct question, but I cant seem to find how to rest my AC, I have freon in it and its not getting cold. Also my SLK 280 blowing hot and I check and it also has juice, but I got a waring to reset the AC , so How do I do that for both cars?

richpro

Thanks all for the information provided above. Currently working on 2010 GL450 A/C with rear air (label in engine compartment notes 2.68lbs 134A, NOT 34 oz in earlier post, depends on the options).

This is second known compressor failure, vehicle has 160,000 miles. Last compressor replaced by local shop at 141,300 on 7/2019 for $900. It worked great until drivers side starting getting warm but passenger side would get cool.

MISTAKE: I added the “A/C Pro” with included gauge on the low side according to their instructions and it cooled drivers side for a couple weeks. While turning into a store driveway, lost power steering. Since it was hot here in New Jersey this week (July ‘23), with engine still running, watched thermometer on dash start to climb! Drove a few miles back to the house with temperature rising and warning light to turn off engine. Yes the serpentine belt was off pulleys and bundled up restricting the cooling fan.
Why? See pictures of internally damaged compressor with the seven pistons. The variable drive plate that moves pistons was scarred from what I will assume is lack of lubrication. Several of the bearing discs that transfer movement of each piston were also scarred leaving metallic particles in the compressor housing.
Question: Knowing there is metallic particles in the compressor, did it travel down the high side into the condenser? If particles went into condenser, would they get trapped in the dryer?

Compressor is arriving today and I do not know if the expansion valve/valves (two because of rear air) need to be changed.

Any suggestions? Thanks to the community.
-Rich



Scarred variable plate



Back plate - shows valve in place that meters flow.

Two for each piston. Some were scarred leaving metal particles in the system.

Note the back plate has reed type valves for each piston

Front broke off from hub when compressor locked up


Let me know if any questions.