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dannym 10-16-2004 01:23 PM

Auxilliary fan on a 1984 300SD
Hey everyone,
I have never seen the auxiliary fan come on. I always thought that the fan came on as soon as the AC was started. But being that it has an engine fan that may not be the case.
I did a search and someone said there is another relay or fuse at the fan motor area, is this true?
I also read that it will only come on if the AC gets hot at the sensor on the accumulator.
I also know it's not getting power. Is this normal or should I try to find out why it's not working?



jbaj007 10-16-2004 01:27 PM

Jump the leads to the switch at the receiver/dryer. It is the "upper" switch of the two there. The fan should then come on. On the '84 SD only higher high side refrigerant temp/pressure triggers the aux fan.

alanintn 10-17-2004 12:09 PM

These pressure swithches can go bad. I would replace with only the red colored one. It closes at a lower pressure and will help save compressor life. High pressure = high temperture which = short life of compressor. Also when replacing put a new Reciever dryer in at the same time. They go bad with age alsoand will kill your TXV valve. That is a day and a halfs labor to replace.
My 2 cents. I'm not positive it is red but fastlane nows.

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