Hmmm. 245 psi is getting up there, but its not crazy high. I’ve seen 415 psi in some systems in highly adverse conditions. ( note: worst condition = car parked in front of wall or garage door, engine at idle for long period of time. ) I’m wondering how hot things are getting. Don’t forget that when engine goes to a near overheating condition the engine control computer shuts off the air conditioning system. This ensures the engine is protected from damage and that you can get to your destination.
Edit: One note, when this happens you will get either a check engine light or cooling overtemp light on your instrument cluster..
I’d recommend a full engine cooling inspection. Look hard at the airflow through the A/C condenser and radiator. Excessive bugs stuck in the fins? Are all the air seals in place? Is the cooling fan working correctly? If that fan isn’t working at full speed your A/C will definitely end up going over pressure or the coolant overheat shutdowns will kick in.
Another question. Are you positive there are no air pockets in the cooling system? I believe your vehicle uses a dual seal radiator cap with vacuum overflow return. If your radiator cap doesn’t seal on the vacuum return 1) you won’t get all the air out of the system and 2) the coolant will boil at 212 deg F instead of ~235 deg F.
Coolant quality? Hopefully you have never ever used tap water in your radiator. Thats way bad. Glycol and distilled water only (50% / 50%)
Take a close look at engine cooling stuff, let us know what you find.
Thanks for the feedback. I forgot about the check engine lamp / coolant light. If you are in overheat condition, you will definitely set a lamp. And I think you would have said something by now...
This posting got me to pull out the book on refrigerant stats. I believe you have a Orifice tube / suction side pressure control system. Above 90 degrees F, that system will go on and stay on. It would only cycle below 90 degrees.
A good test is to run the A/C in the morning, say around 80 degrees F. At steady state in a normal system, the A/C clutch should run for around 70 seconds, then off for 10 seconds. I'd love to know if yours runs this way in the early morning. Its possible that the pressure switch on the accumulator bottle is broken. The good news is they are quite easy to change. They spin off by hand, and there is a schroeder valve underneath the switch to retain refrigerant. My guess is that switch is broken, and when it tries to cycle, it goes open circuit and gets stuck there.