AC one side cold another warm. Please help!




support@icarsoft.us
and explain the current findings. I wrote them a few weeks back with some questions, and got a quick answer from Barnett Davies.
Or call them directly at 1-703-890-6001




After spending some time for driving cycle required for regeneration, the scanner show me filter load close to 0, but after restarting everything, the number did not change from before regeneration.
That is why I did not hesitate to spend $49 when Autel dongle come on the market.
I am also looking at the OpenPort 2.0 (TacTrix) dongle of which there are 3 versions: old black one, new gold A and new gold B. A bit of research ahead before committing to installing the Xentry pass-thru Surya (Prihadi) posted. Rebuilt laptop for Xentry only use waiting in the garage.




If W212 can communicate with N70/OCP and get correct N70b1 data, there is no reason N22/7 HVAC can't do the same.
Same CAN B highway used.
Maybe iCarsoft implementation of the A22/7 is based on non-CAN BUS N70 (like my car ) where there are hardwires for the N70b1 NTC positioned at N70 but owned by N22/7 HVAC.
So -50C value is NO DATA value aka no-connection, as iCarsoft expected OP's N22/7 HVAC to have that data by hardwires.
Good thing OP's N70 is of CAN-BUS type and can produce the N70b1 temperature data.




AC module:
B10/4 78.98 F
B10/6 37.58 F
B10/31 44.05 F
B10/32 44.06 F
B10/35 54.50 F <-- is this expected?
B10/36 68.9 F <-- Same?
B11/4 186.80 F
B14 106.70 F
N70b1 -58.F
RPM 1966
Power Consumption 0.7 A
Refrigerant Pressure 221.91 PSI
OCP Module
Temperature interior 70.25 F
Fan ON
Hope the above helps,
Last edited by JCM_MB; Sep 9, 2021 at 03:19 PM.




B10/36 68.9 F <-- Same?
Above is Left and Right footwell temp sensor. Usually it is hotter a bit, 1st is from firewall heat and 2nd is by longer distance from EVAP core and poorer insulation.
B10/31 Left side air outlet temperature sensor
B10/32 Right side air outlet temperature sensor
B10/35 Left front footwell air outlet temperature sensor
B10/36 Right front footwell air outlet temperature sensor
B10/4 Interior temperature sensor
B10/6 Evaporator temperature sensor
After engine shut down, I notice reading these 2 sensors I get approx 2-3C hotter than the rest.




I guess the vent mode was selected up over the face or blower was on manual-slow so these values are kind of consistent, not off the scale.
It's not like we enjoy taking apart these E-Class just for giggles and look at wirings... 🙂
Noted the crazy iCarsoft "N70b1= -58.F"... bug!
Last edited by CaliBenzDriver; Sep 9, 2021 at 11:33 PM.
AC module:
B10/4 78.98 F
B10/6 37.58 F
B10/31 44.05 F
B10/32 44.06 F
B10/35 54.50 F <-- is this expected?
B10/36 68.9 F <-- Same?
B11/4 186.80 F
B14 106.70 F
N70b1 -58.F
RPM 1966
Power Consumption 0.7 A
Refrigerant Pressure 221.91 PSI
OCP Module
Temperature interior 70.25 F
Fan ON
Hope the above helps,
I suspect my freon level is low but not hitting the warning limit.
My next step is to do some gauge measurements on the low and high side pressure values in a workshop.
Will update. Thanks
You have a leak. Pretty simple. Leaks cause all kinds of not-working AC stuff. Since you're lucky enough to still have pressure in the system, start spraying down your connections with soapy water. These cars are getting old.
Once you find the leak and fix it, pull vacuum and throw an exact charge in it. I think it's 21oz or something. Check the core support or wherever it is. I say exact charge so you have an absolute baseline. If you don't know exactly what you put in it, you'll chase pressures forever. Fun, if you have nothing better to do, otherwise not so much.
The Best of Mercedes & AMG




Very seldom there is an issue that sensor test will not answer.
This topic is so stirred, that I can't make sense out of it.
I am in luck, the ac do not have any complicated problem and also, I can learn a lot in MB ac system and electronic, as well as doing ac health check.
For your reference, the refrigerant pressure is now around 14 to 15 bar when ac is on. The evaporator temp is about 8c. The air blowing out is ice cold.... : )
Thanks once again. The MBworld is full of knowledgeable, helpful and nice people. Happy driving all!
I am in luck, the ac do not have any complicated problem and also, I can learn a lot in MB ac system and electronic, as well as doing ac health check.
For your reference, the refrigerant pressure is now around 14 to 15 bar when ac is on. The evaporator temp is about 8c. The air blowing out is ice cold.... : )
Thanks once again. The MBworld is full of knowledgeable, helpful and nice people. Happy driving all!
For future searchers:
Post #2 is the solution to this thread.
Last edited by Senecat; Sep 16, 2021 at 11:15 PM.




14 to 15 bars max is still low pressure.
The system should max in high 20's of bars, when stabilizing at at least 17 bars after some time. My evaporator reads 2-3C most of the time.
8C is not ice cold, so sounds like Placebo effect tinted the judgement.




14 to 15 bars max is still low pressure.
The system should max in high 20's of bars, when stabilizing at at least 17 bars after some time. My evaporator reads 2-3C most of the time.
8C is not ice cold, so sounds like Placebo effect tinted the judgement.
From my measurements, the evaporator temperature matches yours as well, i.e. 37.6F -> 3.1 C.

===========
Separately: I tested a temporary update of the iCarSoft software, but issue still remains waiting for next feedback..
Last edited by JCM_MB; Sep 17, 2021 at 10:58 AM.
14 to 15 bars max is still low pressure.
The system should max in high 20's of bars, when stabilizing at at least 17 bars after some time. My evaporator reads 2-3C most of the time.
8C is not ice cold, so sounds like Placebo effect tinted the judgement.




From my measurements, the evaporator temperature matches yours as well, i.e. 37.6F -> 3.1 C.

===========
Separately: I tested a temporary update of the iCarSoft software, but issue still remains waiting for next feedback..
8 degree C is measured when the engine was running for just a few minutes. Will have a check of evaporator temp again after driving for an hour or so.




Is there a logic in the system that when A/C cooling capasity is compromised cool air is directed only to the driver's side?




Is there a logic in the system that when A/C cooling capasity is compromised cool air is directed only to the driver's side?
Well known fact since W210 era.
W212 are much newer cars, so those problems only begin to be common.




Just wondering about the logic of directing cool air to the driver under limited cooling condition as in this case cooler air comes out on right side that happens to be the driver’s side. There has been many cases in the forum where the cooler air comes out in the left side and I think all of these are left side drivers.
I would really not be surprised if Mercedes build a control logic like this as they sometimes seem to think about situations that you would not.
No evap coil I've ever seen (thousands, including commercial, residential, auto, etc.) has ever gotten "colder on 1 side" than the other. @Arrie explains basic coil design in his #95 post. W210 guys don't have a clue what they are talking about. I'd also be more inclined to believe that Benz would have been alerted to and rectified such a "well known fact"/issue long before the first 210 rolled off the line, much less within the span of three generations.
I agree with Arrie; The BCM is reacting to data from the ten thousand sensors and actuating dampers automatically to focus on the driver under fail mode situations. One of those things that makes so much sense, you wonder why you never though of it yourself!




A parallel tubes connection in cars does exist in the front of the car as the engine cooling radiator is built like that and it can have different temperatures and heat exchange ratios across the tubes but this has nothing to do with A/C.


