[ethangsmith]

This started last night. I was driving home and the A/C (still original R12) was working just fine. Then all of a sudden the compressor stopped cycling (you can hear it and feel it when it does) and the radiator fan started to "short cycle" as in it's on for 1 second, off for one second. This morning I checked again and the compressor is not cycling. The clutch is not engaging at all and the fan is still running in its 1 second bursts. Is this a failure of the fan controller under the dash? Or is this caused by either a compressor failure or pressure switch issue?

[90 stock stang]

Might be an issue with the wiring having a bad connection or short as for the compressor I had an 88 gt that had an issue with the compressor when it got older it would work fine but you had to turn on the switch in the car then pop the hood and hit the compressor hub in the front with the end of your fist to get the compressor to engage.

[ethangsmith]

I jumpered out the fan switch on the engine (to simulate a hot engine) and the fan turns on and runs fine. I'm almost wondering if you hit the nail on the head with your idea about it being a bad compressor clutch. Seems like occasionally it tries to engage but it will for only a second or 2, but that is rarely and I have yet to actually see the compressor clutch engage and spin. I am almost wondering if the pressure switch went bad and is causing this.