pumpedTSI

My AC quit working the other day after it has been working fine......warm air from all vents. The weather here in Miami has been in the high 90's and even broke 100 a few days so no AC is not an option. My compressor was running and my gas charge pressures were good so I figured it was a control/sensor issue.
I did a bit of reading about the issue and then plugged in the STAR diagnostics which told me that the interior temp sensor unit was defective. This sensor is apparently part of the entire digital display/temp control/fan speed control unit on the later model W220. Anyways, I removed the entire assembly and while out I split the unit by carefully releasing the plastic snap in clips.....the front control portion of the assembly is connected to the rear by a large ribbon cable which I did not disturb. I looked at the temp sensor (thermistor) and noticed that it had a large ball of "fluff" on the sensor and some fluff in the tube the sensor fits in....removed it VERY carefully with a small screwdriver and blew it all out nice and clean. Assembled the unit and reinstalled the unit for testing.......45 degrees all day long......FIXED!!
Very happy with the results.....hope it helps someone else.....

amstel78

Nice job! Is yours a W220 or W221? On the W220, I believe the thermistor is located in the roof console housing the map lights.

pumpedTSI

Mine is a later model W220 (S55 AMG) and the temp sensor (thermistor) is actually part of the front panel climate controls and NOT on the overhead console like the earlier model 220......that one is particularly delicate to touch or repair since the wires are so thin....

maw1124

Thanks for this. I'm going to blow compressed air at mine now. Won't be taking it apart though...

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Cheers,

maw