When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
AC in the W210 E55 has been failing this past week. Starts blowing cold air as normal and then just shuts off. Start AC, it runs fine for five to six minutes, and then the compressor clutch just disconnects. Turn car off, restart, and it repeats exactly the same.
I used the AAC keypad to interrogate the sensor values plus a pressure gauge on the access port on the low pressure side. It took me a bit of time but I succeeded. I recommend you monitor each sensor from start until failure of the unit; eventually you will find the problem sensor.
Mine turned out to be sensor #5; the evaporator core temperature sensor. Start the AC, core drops to 49* F, then, a few minutes later, the sensor value jumps to 138*F for several seconds and then back down to normal. Meanwhile, as soon as the sensor reads 138* F, the compressor clutch disengages and stays disengaged until the car is powered off. Power off, restart, and the process would repeat.
Exact same problem about 2 years ago. Now the EC light's on again - it seems it's something every year with the AC. It's never been adequate to keep up with Georgia's summer heat-n-humidity since new. My Japanese cars AC's are 5X as strong and never seem to have issues. I trust the modern ones are better engineered.
if you cant manually turn the EC light off, then you have a fault. do the diagnostics as explained above to determine the fault,however when all is said and done you have a leak and low in refrigerant.
02-20-2022, 06:15 PM
