Calling A/C techs...
I had a theory about the problem, but I'd like to confer before proceeding.
A/C system was working last 2 years, but now it only cycles for ~10 seconds, then shuts off until I cycle the A/C (or defrost) off/on. Does this every time, no matter how long I wait between A/C cycles.
Belts are tight, no clutch slippage (that I can observe) and the engine DOES idle up when running (pulser is gapped to spec)
Hooked up the R-12 gauge and there were the readings:
Engine at EOT, system off:
Low side: ~50 psi
HIgh side: 55 psi
Low: drops to ~0 psi quickly
High: raises to ~75-85 and holds
Low: raises to ~55-60 psi
High: drops to ~60 psi
I added less than 5oz of R12, but same result, only the high side raises slightly, but the low raises when the system is not cycling. Before I add (or maybe waste if the receiver/drier needs replaced) any more, I just wanted to confirm that it just might be low on R12 and the trinary switch is deactiviating due to low pressure.