Aux Fan Controller and 4-pin Connector 95 S320 W140
 

Hi All:

I need some assistance. My auxillary fans are not turning on anymore. The only time they spin at all is when the a/c is on (and they seem to be operating from the high-pressure switch from the a/c system).

My question is this: Does that sound like the controller module? And if so, where is it located. I have a 1995 S320 W140 model.

One more thing, the 4-pin connector on the engine block with the temperature sensor that is somehow connected to the fans, can anyone give me the correct wiring colors to correspond with the numbers on the pin connector? I think the previous owner may have re-wired the plug and may have snapped it into the connector backwards.

I appreciate any help and advice out there!

Thanks!

Andrew

What makes you think you have a problem? Aux fans only come on when either:

1. High-side AC pressure exceeds a limit

or

2. Engine coolant temp exceeds a limit (about 105-110 if memory serves - don't quote me on this).


They are principally designed to protect the compressor, not for engine cooling.

Thanks for the reply
 

The fans are not coming on at the high engine temp., only working with the high side a/c.

Thanks, 95 S320 LWB

Aux fans on that car & most 1988-95 MB's come on with engine temps at 107C....does your engine get that hot? with a/c off??

Not Usually
 

I have a cool harness from Jim F. installed, but with the a/c running and the temperature hot outside, it will go over the 100 degree mark without the fans going on full blast.

Is there a way to jump the pins on the switch to check the operation?

Thanks...