My 1994 K1500 has had a recurring problem. Started out that if I had the A/C
on and hit a good sized bump, the A/C would click on and off. Progressively
this has gotten worse where the A/C will click on and off in rapid succession
several times per second. Now it's pretty much any time I turn the A/C or
fan or anything on, and I hit a bump, it starts turning on and off in rapid
succession. This may go on for 5 or 10 minutes and then the control unit
goes dark and the thing sticks in whatever mode it was in prior (fan high,
etc.). Which this turning on and off is an audible click that's coming from
the cluster of relays / resisters in the dash.
I first thought this was the controller so picked up a used one at the
junkyard but that didn't do anything. I tried wiggling the connections into
the relays in the dash and that also didn't do anything.
Only other thing that may help trouble shooting - since this started, I can't
get the air to blow out of the front vents, only the defrost and I think the
floor vents too - regardless of what the controller is set at.