Auxiliary Fan

Ohmess

Ohmess

I wanna DRIVE!
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I believe I have the stock Aux fan in my coupe, and that it is not working. Neither my owner's manual nor my big print wiring diagram contain a schematic for the circuit that powers this fan, and if possible I would like to get it working, at least temporarily.

Realoem shows two relays and a temperature switch as parts associated with my car. Not sure where the temperature input would come from as the only output from the coolant temperature sensor in the tstat housing is connected to the gauge in the dash.

Does anyone have a schematic of this circuit?
 
As you own a 72 it only comes on with the A/C system. In 74 they added that other relay and sensor unit. It was discussed about two months ago I think.

When A/C unit is turned on, power goes to round relay under the coil and also direct to the compressor. It energizes the relay to turn on the fan. The relay doesn't turn on the compressor.
 
Yes but it is controlled by the temp switch, if the cabin temp drops low enough (say at night) it will cycle the compressor and fan on and off.

HB Chris said:
As you own a 72 it only comes on with the A/C system. In 74 they added that other relay and sensor unit. It was discussed about two months ago I think.

When A/C unit is turned on, power goes to round relay under the coil and also direct to the compressor. It energizes the relay to turn on the fan. The relay doesn't turn on the compressor.
Click to expand...
 
We are saying the same thing, A/C and aux fan controlled by Temp switch, but not fan by radiator temp except on later coupes. It just seems strange that the compressor is wired directly and only the fan runs from the relay.
 
Easy to put a diode in line from the compressor to relay and add wire from temp sensor to same pin.
 
Somebody here sent me the diagram, I can look for it when I am back home.
 
Thanks a ton guys. I'll check the circuit to the relay and the performance of the relay itself. Should be relatively easy to get the fan turning.

Don -- I likely will be adopting your suggestion to replace the existing aux fan with an e24/e28 fan, rewiring the fan to run off coolant temp rather than off the a/c switch (assuming I can figure out a location for the temp sensor that activates the fan. My tstat housing has only one port for a sensor).
 
You need a 82C sensor at bottom right of radiator.
 
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