1986 300E A/C compressor and Aux fan not engaging. Earlier today I added 12oz R134a freon via the low pressure port (I had a slow leak), and the A/C was working great. Later I removed the left rear tail light assembly (found some rust and needs new seal), but when I restarted the car the A/C did not work. Shorting the wires to the pressure switch on the receiver/drier had no effect. Fuse to A/C is good. ???

 

This must be associated with the tail lights. I have both taillights pulled from the housing and sitting in the trunk while attending to some surface rust, and the A/C compressor and aux fan are working again.

 

It wasn’t associated with the taillights. I had recently replaced this engine coolant temp sensor on my 1986 300E, and the aux fan would then go to high speed when the engine temp went up. However the A/C and Aux fan low speed would quit working after the car had been run awhile, but was not overheating. I pulled the single connector wire off the sensor and the A/C and aux fan low speed are working again. Wrong part???

 

Found this part which supposedly superseded the green one. Have it on order.

https://www.autohausaz.com/pn/006545...AAZ42325&gQT=0

 

You are purchasing these parts from all the wrong places. My priority on order are:
(1) Dealership
(2) AutohausAZ/FCP Euro/Pelican parts.

I have been maintaining the original to me '89 W201 with M103 engine for a long time now.
Never have gotten an incorrect part from the dealership. and very seldom if at all from the other 3 listed.

Also remember that your AC will be disabled until the engine is turned off if there are any fault cases sensed.
One of these is a slippage of the fan belt. I think you are finding out the other fault cases. I was not aware of those.

- Cheers!

 

thanks, I’ve ordered a replacement from AutohausAZ.