tobe1424

Hello folks,

A couple of days ago the AC in my 2010 e350 with about 115K miles started blowing hot air. My wife was entering the highway onramp when she claimed the “transmission slipped” and all of a sudden the AC went from blowing cold air to blowing hot air.

About 6months ago I had a torque converter shutter and the occasional slip. However, I believe that was a result of the old fluid and the car sitting for too long. After changing the fluid and resetting the TCM, the transmission went back to normal.

Down here in South Florida, we’ve had consecutive days with generous amounts of rain. My wife claims she drove cautiously through a handful of puddles. The car is missing a splash shield making the bottom of the engine exposed to the elements.

I connected my autel scanner and picked up a few codes. The first 2 codes are old. I replaced the manifold so I am not sure why 0524 keeps returning. 0155 is there from months back after I ripped the sensor of the thermostat. 0407 is new to me. The stored oxygen sensor codes don’t concern me.

As well, 6 months ago my AC was blowing hot from half of the vents. The other half was barely cold. I took the car to my local Indy shop. Mercedes Mike down here in Pompano is a great dude.

Anyway, he emptied the system and added new refrigerant. I remember him using this Xentry tool to look at the refrigerant levels. I forgot exactly what he considered low but I am able to view the same readings with my autel. I used some of the other AC diagnostics features in the tools but I didn't see anything out of the norm.

Do you guys think the refrigerant readings are low? I find it very weird that in a split second, the ac went from freezing cold to hot.

I really appreciate any help you can provide.








I believe this is the low side hence the "-" sign

I believe this is the high side "+"

CaliBenzDriver

Good job with your advanced troubleshooting.

You've rulled out a lot of things. System numbers show it is mostly running but without great cooling.

> I am going to volunteer a sticky proportioning valve.

@juanmor40 and @S-Prihadi are seasoned experts at tropical HVAC output. They should be able to make you chill soon.

Get the belly pan back on before your alternator diodes & brushes get salted like a Margarita.

tobe1424

Thank you very much CalidBenzDriver. You've always helped me get to the bottom of my issues. Very well noted with respect to not having a margarita in my alternator lol. I will look for the shield this week.

In any case, isn't the proportioning valve related to brakes? Or are you referring to the expansion valve or control valve?

Cheers

Rob

CaliBenzDriver

Rob, our cars use the best Japanese compressors with both a clutch AND a proportional valve located at the compressor back side.

This is done to adjust the compressor output and decrease engine load.

Practically the compressor can be spinning with clutch-ON and still pump nothing at all.

Same idea with TX-Valve that controls refrigerant flow to prevent freezing the evaporator.
You can have high pressure available and still no cooling. To prevent that situation, compressor duty is consequently reduced.

Old systems used to be synonymous with high pressures, not so anymore. I think your 128PSI pressure is low but can be expected.

Maybe your TXV is jammed, we'll see....
✌️

S-Prihadi

Tobe,

Since our HVAC operation , the final decision to turn it ON or OFF is by the ECM and not simply by the N22/7 HVAC controller only, the tranny issue could also
make ECM to cut off load or reduce load from the engine. It can cut off alternator and HVAC compressor as part of its torque management.
Alternator and HVAC is big load, at peak power consumption these two can be worth 4 HP of parasitic load on the engine.

Now the way to read the scanner page below :


.



ZB61 is the refrigerant flow solenoid. Its maximum power to it , is up to 1.0 amp. Usually 0.95A is max in normal healthy HVAC operation.
Refrigerant pressure is temperature and compression based, when HVAC compressor is running properly.
When good EVAP temperature is reached, for mine is 2C to 3Celsius, the power to the compressor refrigerant flow solenoid is cut to approx 0.50 to 0.60 amp.

When engine and all HVAC components are already at ambient temperature, say 12 hours after engine kill, you can use the R134A pressure-temperature charge as arough guide that
there is R134A in the HVAC system, but it does not tell the proper charge/fill level of the R134A.

Download this : https://www.igasusa.com/pt-charts/R134A-PT-Chart.pdf

Now I have to assume a few things, because R134A pressure is temperature based ( before compressor compressed R134A further ) :
01. I assumme the scanner readings, both of them are when your engine just started and in under 1 minute of engine running.
02. I assume your car is parked at a very shaded location, as such the evap temperature of 101.3 F is the ambient temperature at that particulat moment in time.

Based on assumption 1 and 2 , the R134A pressure you are seeing at 118 to 121 PSI, is actually the R134A normal un-compressed by compressor (+-5 psi tolerance),
pressure when and if at 101F temperature. Damn, are you sure the ambient temperature at that moment is that hot ? 101F = 38C ...... hot hot hot



If 101F / 38C was not your ambient temperature of the day ( use the car ambient temp sensor at front bumper ) or your own thermometer
Now, if you can re-do the scanning again when engine been killed for 12 hours, please do not turn ON the engine yet and the HVAC compressor.

AA. Take the actual ambient temp reading and the pressure reading first, using Ignition Key ON engine OFF.

BB. Next, take the scanner reading again 2 minutes after engine running, and then you turn ON the HVAC compressor set at max cold and blower at max too.


FYI, Xentry or any scanner , CAN NOT indicate proper amount of R134A fill in any HVAC system.
You see, at a mere 20% fill capacity by grams/weight, or 80% short of proper fill capacity, your HVAC system will already give a proper R134A pressure-temperature value.
It is the nature of R134A that it is 20% liquid state and 80% gas state when at rest or saturated pressure HVAC dudes will call it.
So the only way to know proper fill state of an HVAC system is to evacuate the R134A into a special recovery tank with a 5 gram accurate scale under the recovery bottle.
And compare it to the R134A fill weight table as per the sticker at engine bay or MB WIS. My car is a 590 grams R134A , single evap.

Do a proper vacuum on the HVAC system down to at least 350-400 microns if car is as old as yours/mine and this 350-400 microns is to be read at HP port,
while vacuum happened at LP port only. This will take easy 5+ hours or never achievable when using the stupid small 1/4" hose at 6 feet long.

When the HVAC system is dry enough at a true under 500 microns, the techy will then charge if possible using a new virgin fresh and not recycled/captured R134A
to your HVAC system.

Test AA and BB will the confirm if the refrigerant solenoid or what Cali called as proportioning valve ( refrigerant flow valve ) in indeed stuck closed or not.
Here again I have to assume that you have inspected the connector to the HVAC proportioning valve as good and if possible back probe it
to read the duty cycle commanded to it reaching the valve.

Oky doky..... start the troubleshooting please.

tobe1424

Thank you so much guys! I can't express how grateful I am for the immense amount of knowledge you are sharing.

You are correctly assuming that my readings were performed shortly after turning on the car. However, it wasn't in the shade and the ambient temperature of 101 is accurate. Although it's in the high 80's it feels a lot hotter when your standing outside. I live in south east Florida about a mile from the ocean and between 11-4pm the sun is beaming down on my cars. My other car/truck reads similar ambient temperatures.

I don't own HVAC equipment so I might have to bite the bullet and take it to my Indy shop(mercedes Mike) and with your exact instructions.

tobe1424

After a few conversations with Daniel(owner) which reiterated some of your advise, I dropped of the car at MBZ-One world in pompano beach. This was the based the refrigerant base reading:




Initial refrigerant reading. After a 10 minute drive to the shop with the compressor turned off until arriving.

tobe1424

I just received an update from Daniel. He claims the alternator is not charging properly. He claims the voltage is low which causes the compressor not to start. He will further troubleshoot and get back to me.


At idle.

S-Prihadi

Tell him to turn on HVAC to full maximum blower speed and coldness, that will force the alternator's stupid power savings control to be de-activated and you get a true alternator voltage.
Our W212 can on purpose give that lower than 12.6V alternator voltage output

S-Prihadi

Wow, 15 psi only , assuming the condenser being cooled by ambient air temp of 81F.
That is way too low, aka you lost a lot of refrigerant. I bet when evacuated it will be no more than 50 grams or approx 1.7 ounce only of R134A, or less.
This means you have a leak somewhere.


If the Robinair RRR machine he is using is that model, the vacuum pump is so small at 1.5CFM ( page 5 ). No micron meter too, only useless analog vacuum gauge.
If he allows, do minimum 1+ hours of vacuuming to dry your HVAC system better than the typical 10-20 minutes ( page 18 ) programmed on the machine.
For page 5 and 18 https://www.robinair.com/sites/defau...C%2520EN_1.pdf
Ask him does his shop has a stand alone micron gauge ?, I hope they have one. Install it at HP port and do final vacuuming at only the LP port.

I don't mean to scare you, but I hope he has the refrigerant analyzer which I doubt his shop will have ( too expensive at US$3.5K+ ).
That RRR machine collects other cars R134A too, so it previous car has contamination of other refrigerant type, you get some too.

For him to give you virgin R134A accurately by weigh it is very troublesome on RRR machine like that.
Unless he has a stand alone 2 - 5 grams accurate scale and a fresh new 30lbs R134A new bottle

tobe1424

Thanks again for the information. I can't thank you enough for your feedback.

Here is what he wants to replace and the reasons along with my intentions.Hi Robert

The estimate is the following

1) alternator $554 - Proper test indicate it's not close to 13.5-14.1 even with the AC on max

Labor alternator$245 - I'm going the DIY route



2) pulley ( groved), serpentine belt $156 - easy peezy

Labor $175 - I'm going the DIY route

3)A/C Compressor $619.56 - He claims he added direct power to the compressor and it still did not turn on.

Dryer $91.45

Labor $985 - I may not be able to take the DIY route. I might be able to remove and install but I still need to vacuum and charge. I don't have these tools. Still, that's a lot of $$$$



4) Main Bosch Battery $339 - He claims the battery wasn't the correct one to begin with; CCA are too low. I always felt like the car is a bit weak when starting up. He claims this could have been the root of all causes.

Labor battery / reset $105. - I'm going the DIY route

Daniel
--

By the way yesterday morning was about 81 degrees F. My instincts tell me to fix the charge system first. Then see if the ac system comes alive. I still can't get over the fact that the AC was freezing cold one moment and blowing hot air the second. If it was a major leak, wouldn't it have zero pressure? Otherwise, the compressor sounds like a culprit as a result of a weak charging system. I'm spit balling here but it seems like the property troubleshoot methodology.

Thoughts?

S-Prihadi

At 115K miles your wear and tear on the alternator , if its winding and diode bridge is still healthy , the parts to replace is the voltage regulator with its carbon brush.
The carbon brush is the one which wears out first as it is a primitive "rubbing" mechanism.

Battery , get a Varta Silver AGM if USA has it. That is the OE of Mercedes.
Must be DIY for sure. There is no reset when replacing battery, BMW has special new battery reset feature, W212 does not.


Pulley or also tensioner ? Best to replace all pulleys (2) and also tensioner ( has pulley too ) , belt too.


HVAC.
It is a big leak but probably not broken or torn hose, as such not yet zero psi today.
You need to replace also the 2 schrader valve , one each at LP and HP port. They do leak too. Genuine one from MB. US$15 ish each I think in USA.

The most expensive single purpose tool is my HVAC DIY hardware set, I spent like almost US$5K+ for a complete DIY system far superior than what
Daniel's workshop uses, that single RRR robinair machine. But mine is a 3 separate units and not a single machine RRR.

The only tool I do not own and will never buy : is the refrigerant gas analyzer, which I do not need as I buy and use only virgin R134A and from proper source, so I do not get fake one.
https://www.valuetesters.com/neutron...1234-40-0.html
Holy F*** , the price this end of year is so expensive. Was like near US$4K only I last saw last time...DUGGHHH.

But to be honest, I really love doing HVAC DIY to perfection as no shop will want to vacuum down a car HVAC for 12+ hours.
But I do not enjoy or would want to tear down my EVAP, because the entire dashboard has to be out of the car.
Hence I am on a very EARLY preventive mode maintenance campaign, hoping my EVAP will last 20 years.


Now here is something you need to know, for knowledge sake.
R134A refrigerant in our HVAC system has 2 stage of being, gas state and liquid state, depending on at EVAP or at Condenser and the pressure.
When R134A fill level is low, the compressor oil circulation becomes bad, because R134A is the oil carrier within the HVAC system.
So what will happen at low R134A fill/charge level is, compressor oil will become accumulated a lot ( too much ) at the EVAP, instead of going back to the compressor.
This is how compressor slowly get damaged from lack of lubrication and the final destiny is the Black Death if fast corrective measure is ignored.

Here is the animation of what I am talking about : It is called lubrication drop out

Natural loss of R134A at shaft seal natural leak is supposedly 4-7 grams a year modern car. The less you use your car, the drier the shaft seal get, the more R134A will leak.
If MB Indonesia was accurate to 5 grams of filling my car R134A charge back in 2013 assembly , when I did the RRR in April 2023, my R134A lost was VERY high.
I made a post on it. https://mbworld.org/forums/e-class-w...ification.html


At that time I have not touch any other cars yet.
Later on when I did RRR on a friend's virgin-untouched-HVAC system , a Japanese made and Japanese assembled Toyota Alphard of approx 7-8 years old,
I see that car's R134A loss is also higher than 4-7grams per year. hhhmmmm.
I have to emphasize Japanese made and Japanese assembled Toyota because supposedly it is the highest standard built of any Toyota.

I then did RRR on my wife's 2020 Thailand assembled Toyota Corolla Cross.
Same thing, wife car's R134A loss is also higher than 4-7grams per year. WTF.

So, it will be my maintenance schedule, that I will now RRR my car once per 2 years, to prevent compressor damage of worst order, the Black Death.
I don't mind the compressor $$ value, what I do not want is removing/throwing the EVAP because the car entire dashboard has to be removed and I do not like that.
Once dashboard removed, there will be minor squeak on bad roads thereafter when re-assembled. I hate those noise. I call the noise cricket concert.

==============
Back to the compressor oil...............

When one replaced his compressor with a new one, he has to do oil balancing to the amount of what was actually in the compressor.
Here we are talking of a HVAC system already used, as in your car, and not a new car HVAC system getting its initial compressor oil fill ( 120cc for my car )
but a decent running used HVAC system and not a very low R134A charged HVAC system.

So, Mercedes WIS has data for what is the oil balancing quantity we need to add when replacing certain components.
If new compressor ( zero oil inside) add 20 cc of compressor oil.




. Below is Filter-drier


New EVAP, new condenser, new hose/s, new IHX ....all has oil quantity value to be added when those components are new one aka oil dry.


Now, ask/remind Daniel to properly measure how much is the oil he managed to collect/drain from your old compressor.
In theory if Mercedes data is correct, it would be approx 20cc.
If your old compressor is very dry, say 5cc oil only, there could be a chance that the 15cc is "stuck" at the evap, during the low R134A charge of you HVAC system and you
were still running the HVAC system.

So this compressor oil is supposed to be wetting the entire HVAC system, even hoses + pipes and will still be proper "X" quantity always at the compressor itself too,
when and if everything is in proper working condition.


Here is a good proof which I have waited for a long time, which is seeing by temperature rise a compressor when its oil been stuck alot at the EVAP,
due to low R134A charge ( or leak ). So internally the compressor operation get increased in temperature from lack of oil lubrication.

Part 1 - when the refrigerant level is still low and the R134A saturated pressure of 49 psi, while yours was last at 15psi.
When he said DISCHARGE temperature, that is him using his thermocouple sensor at the discharge fitting of the compressor , some call it liquid line.
You will see up to 200F discharge temperature. You will also hear his saying the potential of over filling of compessor oil to a new compressor may happen when in such scenario.


Part 2, system recharged to its proper R134A fill level. Discharge tenperature now back to normal ( for the location ambient temperature ) at 127F as now the compressor oil
stuck at EVAP started to migrate back to compressor by the now normal assistance of R134A mass flow.

The final say from Tom the techy is: the said car compressor will still be short lived.
What happened to it has done enough damage.


So please do me a favor :
Ask/remind Daniel to properly measure how much is the oil he managed to collect/drain from your old compressor.


This is typical proper oil balancing of a new compressor when and if EVAP did not have oil "stuck" a lot in it.


.
Have fun doing your DIY

CaliBenzDriver

Rob, you local parts hanger forgot your original concern - He did not identify where is your AC system leaking from... the .50¢ Schrader valves are famous leakers. Spit-test them for free under 5mn

You can replace all the maintenance parts enumerated and still not have any AC - Let's focuss on your primary concern! AC short cycles because it is low on charge
... refrigerant leak.

Besides if your going to evacuate AC, I'd recommend the pressure switch that is known to be troublesome ("Fan runs supersonic") - If you're lucky the pressure sensor/switch will be your leak. 🤞


The W212 Valeo Alternator is one bad touchy device. It is remotely controlled by the Bosch ECU through a serial LIN.
The easiest thing you can do to troubleshoot alternator is to disconnect the LIN connector directly at the rear. This should get you a self-regulated 14.5V.
The reason I mention that is you have a high chance a new/refurb ALT will discfuntion just like the Valeo OEM
Good alternator voltage will go a ling way to charge up your tired battery.

Last is don't just rush to replace the compressor until proven bad... (low high-side?) unless you really want new performance for Floridian humidity.

Arrie

Little confused about the pressure readings. I assume this is when AC compressor is OFF as when running the low side should be something like 35-40 psi and high side like 180-190 psi at 90F outside temperature.

The system can give momentary hot air at WOT event. Your wife says she drove cautiously on a ramp to highway in rain. I'm not saying she does not know what she does but on a slippery road you can floor the gas pedal and car won't accelerate too fast while the ESP controls engine and keeps the wheels from slipping yet the gas pedal being down enough it disables the compressor.

Or did your AC stay not giving cool air? By the gauge readings you had a good charge in the system if the pressures are low and high sides with AC OFF.

S-Prihadi

Tobe,
Wanna invest a bit and learn more of your HVAC system, not for repair works per se, but to verify operational of HVAC and verify if system is dry enough ?
Under US$700 will do.

I agree completely with Cali, the leak has to be found first before final decision.
If the leak is that big, a nitrogen pressure test is good enough, no need expensive R134A sniffer tool.

What I suggest you to invest is not the nitrogen tank and the regulator, but these :

01. Yellow Jacket 41337 Ritchie R134a High Side Coupler 1/4 inch Mf

02. Yellow Jacket 41338 Ritchie R134A Lo-Side Coupler

03 & 04. Appion MGAVCT 1/4" Standard Vacuum-Rated Valve Core Removal Tool. 2 units. https://trutechtools.com/mgavct
Or get two units special price : https://trutechtools.com/appion-mgav...tool-two-pack/
We for R134A system does not actually need its valve core removal capability which is for non-R134A refrigerant, but we need the isolation valve and the
well-built quality of this Appion.

05. Fieldpiece MG44 Job Link Wireless Vacuum Gauge
https://trutechtools.com/fieldpiece-...uum-gauge.html

06 & 07. Fieldpiece JL3PR Job Link Pressure Probe. 2 units. 1 is to become LP and the other to become HP.
https://trutechtools.com/Fieldpiece-...Pressure-Probe

Fieldpiece software is free. Use your own tablet.

You do not need a hose, if you are not charging R134A into your HVAC system.
Item 06 & 07 is the wireless pressure transducer to monitor your LP and HP pressure.....your own tablet as the display.

Item 01 to 04 is basic tool to work on R134A fitting and how to isolate them when you later buy hoses.

Item 05 is a micron gauge, and with item 01 an R134A coupler for HP port and with or without item 03/04 ( isolation valve, vacuum rated ), you can monitor the actual vacuum result at HP port while final vacuum is done at LP port. The "dryness" of a HVAC job vacuuming process can only be verified with a micron gauge, you can't verify it with analog vacuum gauge.
With sensing set-up as described above, do not accept higher than 500 microns and that is a very decent evacuation result.
Here you will learn a lot and in fact it may sadden you when a lot of RRR machine can not do 500 microns with micron set-up as HONEST* ( *challenging ) as above.

If the RRR machine has its own micron gauge, and its hose is 8 feet long ( standard ) and usually at best a 5/16" size, its result will be approx 300 micron better/lower than our own
micron gauge sensing at HP port directly while LP port is where the suction occurs. The vacuum pump of RRR is in the machine itself, its micron sensor is very close to the vacuum pump,
hence the reading is not a true "honest" reading as it is not reading the entire HVAC system of your car.
Your own micron sensor is at your HVAC longest-furthest end, that is the true condition of your car HVAC.
The drier your HVAC system can get, the longer lived the HVAC system will be and the maximum coldness can be achieved as per its design spec.

I must caution you, unless the HVAC guy in the shop is a true HVAC professional with commercial HVAC work experience and he understood your concern,
they probably will kick you out of their workshop when you demand the kind of precision I suggested
Their RRR machine time is money, and vacuuming time is a true bi-etch of any HVAC work in terms of hours spent on a single process of a non-virgin HVAC system aka not as dry as new.
That is why I don't want to go to any HVAC workshop, I do it DIY as I have all the time to do super dry vacuuming in my own garage overnight.

Next time if you want to do proper RRR on your own, another US$3K would do for the other required stand alone machines.
You can get DIY grade quality, no need commercial quality.
Damn I forgot, you can't buy 30 lbs R134A in USA, you need EPA 608/609 HVAC licence : https://www.epa.gov/section608/refri...es-restriction
You as DIY can only buy those jerk-off small cans one, which many are garbage.
Jesus, for HVAC DIY matters.....good thing I don't live in USA

tobe1424

Whoa! You guys are the Merc gods. I can't thank you enough for the massive amounts of knowledge and a helping hand. I need to take a minute to watch the videos. I might be able to work with my home AC guy to get me a 30lbs r134 tank.

I am on the same page with respect to the leak. However, I am tackling the alternator first in an effort to get normal voltage readings. The alternator("new" bosch from rock auto) and pulleys should arrive in a few days.

On the way back from the shop, I tried to turn on the AC using the HVAC controller inside but the AC button flashes red. The blower and functions. However, when I press the Max cool button the AC flashes red a few times and then goes dark.

Now when I go into the ZB61 (Refrigerant Compressor) screen on my Autel, I am reading 0's/zero's all across. Daniel claims he charged the system in an effort to troubleshoot.

Is this an official sign of compressor failure? Maybe he made programming changes with this Xenstar? I say that because he offered to help me "program" the system after I fix the AC myself. With all the knowledge you all are providing, there is no doubt I can fix this myself as well as learn more about hvac which has always been my weakness. I can build you an engine, but I can't charge an ac system. I sense that won't be the case for much longer

@S-Prihadi 01. of the amazon links you sent me is a laptop rather than the high side coupler.

Arrie

Why do you think your alternator is bad if you have 12.5V on the meter? Just because your "Great Guy" wants to change it and make money?

You show ~120 psi pressure readings in your first post, then 15 psi in gauges. Who has these gauges? Your mechanic?

This is sounds so fishy to me...!!!

These cars have "smart" charging system that does not give you 14+ volts at all times. It all depends on the battery charge and power pull demand.

If I want to get my alternator to really work when car idles, I put the fog light ON. For some reason it makes the alternator put out 14+ volts.

The claim that 12.5 volts not being high enough to "start" compressor is BS. These compressors run at all times and output is adjusted internally in the compressor. I have monitored my battery voltage numerous times, and it typically runs 12.5-12.7 volts on highway driving and I never loose cooling. Voltage only goes up if I have head lights or fog light ON or the car decelerates, when the system uses car's kinetic energy to charge battery with higher alternator output.

If I were you I would go get a can of 134a and charge the system and see if there still is a problem.

S-Prihadi

The 1st link is a coupler... I checked.

Anyway...........
Tobe asked #1: Now when I go into the ZB61 (Refrigerant Compressor) screen on my Autel, I am reading 0's/zero's all across. Daniel claims he charged the system in an effort to troubleshoot.
I feel bad for you. If you are reading zero PSI from your car refrigerant pressure sensor which is at the condenser bottom, right after say 24-48 hours Daniel claimed he has charged the system, that kind of leak
of loosing near 600 grams of R134A withing 24-48 hours is very traceable and in fact the RRR machine he usesm, during vacuuming process would be warning of the leak, as it does a short vacuum decay test
for leak check , which is good enough if leak is THAT big.

Tobe asked #2: Is this an official sign of compressor failure? Maybe he made programming changes with this Xenstar?
I would want first to confirm PWM signal at HVAC solenoid is indeed available and then HVAC solenoid did not engage......... that is one way to confirm if HVAC solenoid is dead.
The HVAC solenoid is not sold stand alone by Denso, you must buy complete compressor from Denso.

Tobe wrote #3 : there is no doubt I can fix this myself as well as learn more about hvac which has always been my weakness. I can build you an engine, but I can't charge an ac system. I sense that won't be the case for much longer
If you really want to learn like I did, now that I know how to understand it much faster when I too did not know much at all early 2022........... as long as you want to spend time and learn and have the
proper instrumentation and willing to learn on your own car........ I can help you how to start the "education"