Aux A/C fan running.... why?

[KeyBlazer]

Just chipping away at issues!
On my 87 Sub..
The small Auxilary fan in front of the A/C Condensor runs all the time now when the engine is on.
I am sure it didnt before I pulled the motor..
I assume the is a temp switch or something...
But where or is this something else?

 

[4X4HIGH]

If it's a factory fan it should only come on when the A/C is commanded turned on. Are you sure the A/C switch if off?

 

[KeyBlazer]

Yes, runs no matter if AC is on or not... didnt before!

 

[greedyg76]

odd. Have you check to see if the switch circuit was damaged at all when pulling the motor?

 

[KeyBlazer]

Where is the circuit and where is the switch?

 

[dyeager535]

It's probably plumbed into the AC lines, so it comes on when it detects pressure or something. At least that would be my assumption. Probably a simple two wire connector.

Not sure how it was done, but I know the cars with electric fans had a switch in one of the AC lines for this purpose.

 

[greedyg76]

it's not a pressure switch, the pressure switch only cycles the A/C compressor. The fan is just a simple electrical switch that is wired to the A/C switch in the cab. If the switch is wired to the negative side of the circuit it is possible that you pinched a wire during your motor swap that shorted to ground and causes the fan to run as soon as you turn the key to on. I would just chase the wiring from the fan back.

 

[bigbadchev84]

Is your defrost on?