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My 2007 GL 320 CDI's AC did not cool a bit. Codes said to change auxilary water pump and airvent temp sensor. Did that, and nothing. No more codes, but no cool air. I wanted to change the compressor for an aftermarket one, but the mechanic said it was the solenoid valve. Got one at EBAY for $40 and it could only be activated if you disconnected it from the system, and energized externally, applying 5v. The AC controls could not start the compressor. The mechanic installed the diode as you described in this post and voila.... 4C cool air came out of the vents. AC works fine and it still has the original compressor with an aftermarket selenoid valve.
I added diode 1N4007 (same as yours) to my 2010 GL550 with original AC compressor. It did not work. Should I try different diode 1N5817 or ....?
I also have a 2009 GL550 and I have experienced this same issue. I used to get the same error others in this thread have gotten but I no longer get the error but the AC still does not work. So I followed the directions other have done and my AC still does not work. Does anyone have any suggestions? Up until a few months ago the AC would periodically kick in and blow cold but there was no rhyme or reason to when it would kick in.
What is your solution to the 9006 DTC? Mine is DTC 9007 (MB CarSoft tool) which is defined as a compressor open circuit according to the CarSoft database. I have verified "good" wiring from RCV to molded connector on intake manifold, This is on a 2008 GL 450. Any response is sincerely appreciated.
Which wire do I use, there’s no violet or blue green
Originally Posted by S-Vibes
There are literally pictures in this thread that do just that. If you’re still confused, then take a pic of your wires and post it here and we’ll help you pick out the right one.
What is your solution to the 9006 DTC? Mine is DTC 9007 (MB CarSoft tool) which is defined as a compressor open circuit according to the CarSoft database. I have verified "good" wiring from RCV to molded connector on intake manifold, This is on a 2008 GL 450. Any response is sincerely appreciated.
Update on reported DTC 9007: After replacing remanufactured compressor with new unit,
errors no longer appeared. A/C is functioning as expected, producing very cold air without any issues. Sometimes it is less expensive in the long term (both cash and time spent) to select new parts even if not OEM, but equal than try lesser options.
@S-Vibes or @Lamont Clemons , can you take a bigger picture of the wire you're using, please? And, also a picture of the harness with the image zoomed out so I can see it in relation to the other parts of the engine? I also have a Bluetec, and I want to make sure I'm splicing into the right one. The pictures for the gas engines, unfortunately, don't apply.
@S-Vibes or @Lamont Clemons , can you take a bigger picture of the wire you're using, please? And, also a picture of the harness with the image zoomed out so I can see it in relation to the other parts of the engine? I also have a Bluetec, and I want to make sure I'm splicing into the right one. The pictures for the gas engines, unfortunately, don't apply.
Sorry to miss your req. @crypticresponse , but I see you did take some excellent pics in the other thread. Thanks for adding those.
Update on reported DTC 9007: After replacing remanufactured compressor with new unit,
errors no longer appeared. A/C is functioning as expected, producing very cold air without any issues. Sometimes it is less expensive in the long term (both cash and time spent) to select new parts even if not OEM, but equal than try lesser options.
I had 9006 issues even with a MB compressor installed by a dealer, so it seems to be hit or miss regardless of the source of the compressor.
Hi. I know this is the x164 forum but I have already posted this problem on the w251 forum without too much success. I have a 2006 r350 w251 and it is basically the same platform so I am hoping this section will get more views. I purchased the r350 with the motor in the trunk in pieces so I don't know the history or problems the Ac had before I purchased the car. I fitted a complete used motor and it now runs great but the Ac compressor was siezed. I replaced the compressor, drier and expansion valve with all new parts and vacuumed and recharged with r134. The compressor will not actuate via the dash controls and has a fault code 9006 short to Ac compressor. I can actuate the compressor thru my star system and it blows ice cold. It is showing a fault with the pressure switch but I have swapped out the switch and it is showing 12 bars pressure on the star system. I checked all the pressure switch wiring and have found no problems also I have a 2007 gl x164 which I used to swap out the Ac control module and front Sam but still have the 9006 code. Any ideas or suggestions would be great fully accepted. Thanks
I am going to save you a lot if time, money and energy. If you are getting this code 9006. Remove the new compressor if you already have it installed. and exchange the sensor on the back of the compressor with the one from the old Compressor. Your car computer will not recognize the new after market compressor but it will remember the old one that was in the car.
Have done this some many times with most bmw and Mercedes never fails.
Here's the wire in question on a gas engine (GL 550 in this case). It is by itself inside a ribbed rubber cover that comes up from the compressor behind the power steering reservoir before joining a bunch of other wiring into a common cover on top of the valve cover:
The cover was cut to access the wire
1N4007 diode is inside the black shrink wrap and soldered to the A/C signal wire
i got CL550 2008 looks identical however I can’t figure out where is this blue/green wire. Can you take some photos of where the wire comes from please?
I just put this diode into my daughter's 2006 ML500 today to hopefully stop the intermittent AC.
Anyway I love fixes like this. I didn't even have to get under the car which is at the beginning of the thread
I assume that this mod is fooling some module .
Anybody know what it is doing?
According to one of the threads on the topic, the diode used on the compressor (seems to mostly be an issue with replacement compressors) isn't the correct type or value and adding the second one fixes the issue. It is pretty satisfying to fix it with a $.20 part.
I think he is saying that this mod needs a different diode if the compressor has been changed.
Anyway I would still like to know what this mod is doing to correct the intermittent action of the AC.
Correct. It only seems to be an issue with vehicles that have had their compressors replaced. The brand of the compressor doesn't matter. Mine had a MB branded replacement and it had the issue. If you search for 9006 error codes, you should find several threads on the topic (I think some are in sections other than this one), and someone with an EE background had an explanation of why it worked in one of them. IIRC, It had to do with the signal wire that is being tapped having some kind of spurious interference on it that the diode fixes.
Just to report that my daughter took it on a fairly long trip today and the AC worked perfectly so the trick works.
Hats off to the poster who shared this.
On my 2006 R350 wire is blue with green tracer. Had a few 1N5408 diodes lying around from the blower speed circuitry on my Jag, these are similar to the 1N4007 diode but with a higher amp rating (3amp vs.1amp) so I went ahead a soldered one in this morning.
Happy to report A/C is now working properly again! BTW - the PO may have had the compressor replaced but I'm guessing NOT as the engine/compressor area looked pretty undisturbed/dirty ..so maybe the hack works on cars with OEM compressors too?
04-05-2021, 12:37 PM
