Help, been trying to get the A/C to work. Replaced all components and I'm on my 3rd compressor, dryer and orifice tube. Fan will not come on when A/C switch is in the on position, fan works fine when a/c not on and temperature reaches 210. Suspect ECM, some wires chopped at firewall, car has new HEI, CARB, so some of those wires went to the ECCM fuel control but I'm wondering if maybe a wire was cut to the A/C pressure switch. The A/C tech said the system will not work without the fan operating properly. High side pressure way over spec's not at first but slowly rises. 86 Firebird single fan. Is there a switch I can replace or wire I can check? All fuses been checked, Thanks

 

I have this EXACT same problem...

new ECM did not fix it.

I doubt I have a wiring problem...

I feel that it's a fusable link of some kind.

I even replaced my entire AC system to fix it, including the high pressure switch.

if I cannot find out what the problem is, I am going to just cut the wires to the high-pressure switch, and rig it to turn on the fan via a relay setup I already have installed..

Can someone confirm whether or not the high pressure switch simply turns on the fan, or if it goes through to the ECM, which then turns on the fan?

My fix was to install a manual fan control, 3-way switch...

left=ignition-controlled/middle=off-stock control/right=always on, even with car off (to cool it down if I'm gonna work on it, and I don't want to leave the keys in

however, this is very inconvenient if someone else were to drive my car, because they can really damage the compressor if they aren't careful

does your compressor start cycling on and off? Mine does, and I'm not sure if the high-pressure switch is TELLING the compressor to turn off, or if something else does this in the system.

I have a sneaking suspicion that the darn high-pressure switch is interwoven into the ECM and it will be a pain in the *** to fix it...

hope its a fusable link....