That was exactly the problem! It was interesting to monitor the signal to the clutch. When the engine was at ambient, the clutch engaged as expected. As the engine warmed up, I cycled the AC and you could see a time lag grow between power to the clutch and engagement. One time it took almost a minut...

Regarding wiring troubles, I did wiggle the wires a bit to check for intermittent connections and it didn't matter. It is also probably too repeatable to be intermittent. I have cobbled together a clutch wiring pig tail now with and LED to know when power is present. I plug this into the compressor ...

That is good idea, not sure why I didn't consider that. I think I will monitor signal to clutch as that is easier to do.
Thx

I am trying understand why my AC Compressor clutch sometimes doesn't engage. The most reproducible behavior is as follows Start the Jeep from cold, turn on AC - it works, compressor engages Let Jeep idle for a long time, AC continues to work - Jeep at operating temperature for 10 mins or more. Turn ...