A/C & Heater Switch

[JW]

I need help with the slide switch in the dash that controls the heater and A/C in my 90GW. The heater & A/C fans quit working at the same time. When I slide the switch to A/C the clutch on the compressor doesn't engage either. I tried to test the switch but I could not find any hot leads coming into the switch. Does it need one? Is there a fuse other than the one in the panel that I might be forgetting about? Thanks for the help.

[SLINKY]

the compressor has a low freon switch on it. so if it's low the compressor won't kick in.. there is a way to bypass that switch to get it to kick in for testing but not sure on what it is...

also might want to check the little block mounted on the heater housing make sure the fan motor wire hasn't come off... (facing motor it's left side on heater box halfway down) sometimes the contacts wear our on this block and the connectors don't slide on all the way and come off.

Don't think i was any help but i'd figure i'd try

[bchesley]

Yes there should be a hot wire going to the switch. The compressor not coming on has nothing to do with the fan not working. You need to check the power to and from the fuse box for the AC and heat. If you have power to and from you might need to check the main control panel. The panel with the knobs that slide to the different positions, ac heat defrost. This is where the power to the fan comes from. It tells the fans to blow or not to blow. The hi and low switch is just that, changes fan speed. If you dont have power to the panel in the dash you need to start back tracing to find the break. Good luck!!

[Rex]

Several possiblities here..
My first guess is that the fan resistors may be bad. One for the heater is located on the firewall next to the fan. One for the A/C is located under the dash near the drivers side. They are held in with 2 screws. They will interchange as well. You could try to swap them and see if the heater fan works. The a/c is controled by the fan resisitor, control module located near the resistor, a thermistor located in the a/c unit on passenger's side and the low pressure switch. If I remember right, the clutch will not kick in unless all of these work. You can 'jump" the low pressure switch to see if the clucth engages. Not a good way to check the control unit other than to see if power comes out of it and you will need a wiring diragram to do this. Haynes has one in it. The Thermistor can be jumped as well.
Hope this helps.