Intermittent A/C issue.. NOT POWER FC
 

My A/C seems to work only sometimes. And when it does work it takes about 10 mins before it starts blowing cold. The light on the dash goes on and it starts blowing hot air at all speeds. Sometimes then all of a sudden the compressor seems to kick on and blow cold. The system was flushed and refilled and the compressor looks ok.. any other ideas on the cause?

have you checked for leaks or kinks in the hard lines?

yes, i recently had the whole motor apart replacing all the solenoids and vacuum lines and check the whole system visually

I had a problem long ago with my AC working intermittently. Turns out the thermal switch on the evaporator had a high resistance when closed, so the compressor would sometimes work and sometimes not. Every time I took it in to the dealer it would work fine.

hmmm interesting... do you know what the resistance is supposed to read?

+1. This is a common problem on 5spd FD's and occurs because the thermoswitch is switching a large inductive load directly (for which it is not designed). A properly operating t-switch should have a contact resistance of no more than a few ohms when closed; failed units seem to have several hundred ohms resistance. Rather than replace the thermoswitch, you can still use it to operate a slave relay which inturn can operate the magnetic clutch.

You can, of course, replace the thermoswitch, but it will eventually fail again because some bonehead at the factory has connected it to operate outside of its design parameters. The problem could probably be mitigated with the addition of a damper diode across the t-switch. Automatic models, IIRC, are wired differently and don't suffer from this problem.

In any event, bypassing the t-switch will result in evaporator freeze up unless you cycle the compressor manually.

ok... i guess I have a new weekend project... thanks

Which is what I have been doing :lol:. Will have to look into the slave relay mod.