AC one side cold another warm. Please help!




You will need scanner for W212 to read, but with a dozen of different sensors and sophisticated programs MB incorporate in the system, better do it the right way.
Now, I am thinking of getting a scanner. Any recommendations? ICarsoft MB? V2 or 3?




https://www.homedepot.com/p/Thinkdia...DIAG/316829802
But the explanation of the subscriptions is murky, so read the fine print.
I bought Autel AH2000 a year ago for $49 and it is excelent scanner. I think it was over a year ago and it still works without additional subscription, but I register it for Sprinter and it will not work on my MB sedan without paying more..
Last edited by kajtek1; Aug 4, 2021 at 10:27 AM.




> Maintenance steps:
Remove one unit from both side, Crack open casing, clean, silicon LUBE, reinstall, clear codes check temps are back under control.... call chiropractor for a spinal adjustment

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"Zone" ON
Outside temp: 32C
First, set both side to LOW -> warm air out from faulty side (left), cold air out from the right
Then, turn both sides to HI -> hot air out from both side
Then, turn both sides to LOW again -> warm air out from left, cold air from right.
I am not sure how the mixing flap works. It seems to me that the faulty side could offer warm air normally but can not be able to give out cold air. Is the mixing flap problem?
The Best of Mercedes & AMG
I am not a pro and am confusing if the mixing flap (actuator) could still work but only halfway so it can only move to one side (letting hot air in) but not the other!? Any advice?
I am not a pro and am confusing if the mixing flap (actuator) could still work but only halfway so it can only move to one side (letting hot air in) but not the other!? Any advice?
I should make a video.
Last edited by S. Madman; Aug 5, 2021 at 06:46 AM.
I should make a video.
Will do the circles later today to resuscitate the unit again!
BTW, is it possible that the left (faulty side) footwell temperature sensor is not working anymore so it sends wrong message to the control unit for stopping any cold air mixing?




is this OCP module in the weeds?
This may very explain why the HVAC controller is not freezing the driver any further...
I've being up close with the OCP module, it is dependable.
The HVAC logic is not treating -50C as out of range, so you get no code but as a result no heat either.
Pull the fuse and reset things around (OCP, HVAC,...) to get that temperature sensor back online. Definitely a direction worth looking into!
Do you have any other module faults that seem unrelated and may impact the OCP/HVAC CAN-B ??
Do clean your tiny fan up in the OCP... packed with cabin dust!! -50C reading may be a Benz trick to get your attention (ie. $$$$).

Last edited by CaliBenzDriver; Aug 24, 2021 at 12:25 AM.




Get to the car in the morning before sun can hit it and without starting the engine read all the sensors.
All temperatures should be the same, what should confirm the bad sensor as well.








Few years back, Turkish owner of W210 went into measuring thermistor and replacing thermistor only. I remember the fix cost him about 2 bucks, but some time for ordering and soldering.
is this OCP module in the weeds?
This may very explain why the HVAC controller is not freezing the driver any further...
I've being up close with the OCP module, it is dependable.
The HVAC logic is not treating -50C as out of range, so you get no code but as a result no heat either.
Pull the fuse and reset things around (OCP, HVAC,...) to get that temperature sensor back online. Definitely a direction worth looking into!
Do you have any other module faults that seem unrelated and may impact the OCP/HVAC CAN-B ??
Do clean your tiny fan up in the OCP... packed with cabin dust!! -50C reading may be a Benz trick to get your attention (ie. $$$$).

A quick test on AC done. Luckily, no issue....
Last edited by My W212; Aug 24, 2021 at 02:08 AM.




BTW in this thread your pressure is shown to climb to 13Bar, which is good sign 👍
Last edited by My W212; Aug 29, 2021 at 02:00 AM.
The above said that the compressor is controlled by temperature inputs from the sensors. If this is the case, the faulty OCP temp sensor should firstly be dealt with in order to avoid sending wrong signal (my case is -50C) to the compressor and asking the compressor to stop producing enough pressure for cooling.
Please help if you have any advice. Million thanks.



