Elec cooling fan not working when the a/c is on
 

My 1986 928 aux electric cooling fan does not kick on when the a/c is turned on. My guess is that freon temperature switch is not working. I have checked for power at the switch and it is there. My mechanic said he checked it and that it is ok and that the proper amount of a/c is in the sytem. My mechanic says it could be the a/c on off switch. I've looked at the wiring diagrams and I didnt see the on off switch having anything to do with the fan kicking on. Am I right? It seems that the only thing that kicks that fan on is the "thermoswitch cooling water and the temperature regulator freon." How do you test the freon temp switch? How do you short it ground. Thanks.

The fan only comes on when the coolant temperature reaches a specified point. On most 928s it's rare for the fan to operate unless the ambient temp is high, the ac is on full and the vehicle is in heavy, slow moving traffic.

You can check the fan by powering it up with a 12v feed.