The auxiliary fans (dual) are operating at full speed as soon as the ignition is turned on my 400e 93 (m119 engine). I've checked the fuse, but not the relay. It is my understanding the "full speed" aux fan condition is normally caused by short or failure in the coolant temperature sensor creating the low resistance state. Since the fans are not operating at "half or low" speed, I'm NOT suspecting the problem is a result of a pressure sensor on the air conditioner.

Has anyone else had a similar issue? Could the "full fan speed" be a result of a failed auxiliary resistor or is a failed fan resistor characterized by other symptoms other than full fan speed?

Should I begin by checking the ohms on the coolant temp sensor?

Thanks for any help!
Russell

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Russell McMahon
Tulsa, OK
2001 CLK 320
1992 400se
1993 400e
2000 320ML