If you've got 25psi Low Side, Evap Temp is around 27*F so after running awhile, it'll freeze. Once frozen, I think Low Side will drop even farther, and your new LPCO switch will stop the compressor.
If I'm looking at the right Temp/Pressure chart, 50psi will give you a 50*F evaporator. But even if you had 50psi low side, meaning much more refrigerant in the system, the high side shouldn't be above 300psi.
What's your ambient temperature? Any rear wheel drive vehicle is at a disadvantage compared to FWD. That's because FWD uses electric fans that provide full blow at idle/standstill. The RWD's, even with a massive fan and thermal clutch, have trouble cooling a R134A condenser at idle.
Something doesn't seem right. Fan Clutch failed, Radiator Shrouding missing, Condenser plugged with Bugs, Bug Screen in place (they really restrict air flow!), Engine Cooling System overheating... That, or it just can't get the air flow it needs without the coach moving. The old Class C would balk at idle, like stop lights, in Drive. I'd put it in Neutral to take pressure off the system.
Remember, you don't have a high pressure cutoff switch. The LPCO is on the low side. It doesn't care about high side pressure.
I'm gonna take a guess, that if you drive the coach and have a way to keep your gauge set hooked up, you'll see High come down, and also Low, probably to where your LPCO in fact shuts the compressor off.
