333arod333

Hello everyone.

Recently my outside temperature sensor failed and I drove around for about 3 days with the AC working fine. I heard that this sensor failure will cause the AC to stop working, however it took a few days for that to happen. I just replaced the sensor with a genuine Mercedes part and still do not have AC. I did clear all the codes with my scanner and there are no codes present. Is there something else I need to do in order to get the AC to start functioning again?

Thank you for the help

cetialpha5

Just did this myself. It's the same thing when it breaks, A/C works for a while but then completely dies. After I replaced the sensor, I cleared the error code but still no A/C. It takes a few cycles and then it starts working again. I basically played with the A/C a bit and also did several start up and shut downs of the car to go through a few cycles and managed to get it going in the same day. Not sure exactly what did it, basically cycled the a/c from very low to very high temperatures a few times in addition to parking and shutting the car off and then starting it several times.

CaliBenzDriver

The outside temperature sensor data is filtered by algorithm before being used.

A long convoluted logic is used to prevent reading heat from the car own radiator. Ex: when the car is re-started within few hours of shutdown, the last temp while moving before shutdown is displayed.

The key to refresh current temperature straight from sensor is to get the car driving above a threshold speed for sometime. Ex: drive 25mph for 5mn.

/WYSIWYG/... :
This data enhancement by software parallels the processing applied to coolant temperature.... What you see is not raw data.

Consider weatherizing the wiring harness connector to sensor with RTV sealer... plus every exposed connections in the area for no extra charge.

333arod333

Thank you both for the response. I'll let it go through some cycles and see what happens. Thanks again.

CaliBenzDriver

When you put on thinking cap to understand your scanner, a fix is not too far away ✌️

Any other string of faulty modules ??

333arod333

I did use my scan tool to erase the codes and check for others, no other code present on AC control unit or any other modules. Maybe it just needs some cycles to calibrate, hoping so anyway.

konigstiger

https://mbworld.org/forums/e-class-w...ml#post7847084

333arod333

Thank you all for the help. The ac is back to blowing ice cold after a few cycles.

Thank you again

S-Prihadi

AAT sensor is a VIP sensor indeed

cetialpha5

It's pretty crazy how just an outside temperature sensor can take out your whole HVAC system. In the old days with manual controls you turn it for heat, it gave you heat, you turned it for a/c, you got ac, didn't matter what the temperature was.

The first time it died on me, it was the rats or some animal that chewed through the wires, it just died again not too long ago and sometime the tip got chewed up, probably by the same rats/animals.

S-Prihadi

Yes, this AAT sphere of influence is massive...insane to think about it that 1 device looking so simple is heavily relied upon.
https://mbworld.org/forums/e-class-w...ip-sensor.html

It would be wise to observe its value often when at good speed and at traffic jam. If it goes a tiny bad, replace it and verify it works properly.