With all the chatter about the AUX Cooling fans I decided to check the operation of mine last night. Here is what I found...

The AUX cooling fans do not turn on with the A/C. If I pull the plug on the temp sensor (thermostat housing) the fans switch on to high speed, reconnect plug and fans shut off.

As engine warms up the fans will kick on low, and shut off when the engine temp drops.

I did some research back and have found some posting about checking the freon pressure sensor (red w/ 2 leads). I will check this tonight. I have read in the archives about a fuse on the relay for AUX cooling fans, will this fuse only take out the cooling fan from running with the A/C or will it disable them all together.

Any input would be appreciated. Thanks!


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1990 300CE-24
1995 Jeep Wrangler
1995 Ford Thunderbird

Just bridge the wires on the red switch and the fans should come on low...If not, the resistor or the relay fuse is blown.

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Benzmac:
Donnie Drummonds
1992 500E (very soon I hope :)
1981 280GE SWB
ASE CERTIFIED MASTER AUTO TECHNICIAN
SERVICE MANAGER FOR 14 BAY FACILITY
MERCEDES SPECIALIST 8 YRS
PARTNER IN MERCEDESSHOP.COM

Thanks for the reply....I went home and checked it out. Everything appeaars to operating as designed. The cooling fans came on at the low setting when I jumpered the 2 wires. Just for peace of mind I also checked the fuses, and they are ok. Guess I can rest a bit more soundly now.

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1990 300CE-24
1995 Jeep Wrangler
1995 Ford Thunderbird