1st gen Cummins A/C

[hunters628]

I have a 1993 dodge w250 with the ol 5.9 turba deezel. I recently did a r134 retrofit on it and it was working good for a few days then the little plug on the receiver blew out. I replaced the receiver and recharged. Factory charge was 38oz so I replaced with 30oz after doing the math and pressure looked good with that charge. When I did the retrofit I replaced the metering valve, receiver, pump and flushed all lines and evap/condenser. I watched the system run for about an hour and all of a sudden pressure started climbing and by the time I could run and shut the truck off it had reached 350psi on the high side and the air coming out was warm. There should be a high pressure cutoff in this system correct? There is what looks to be a sensing bulb that comes off the suction line and it has a wire coming out of it. Is this the high cutoff? The low pressure cutoff is the one in the metering valve I know that. Hoping one of you guys that knows more about ac will chime in and let me know where to go next.
Thanks
Hunter

 

[bucket]

The high pressure cutoff is just a safety feature for the sake of the compressor. The problem to diagnose is why the pressure got so high.

Normally it's because the fan clutch took a dump.

 

[hunters628]

The high pressure cutoff is just a safety feature for the sake of the compressor. The problem to diagnose is why the pressure got so high.

Normally it's because the fan clutch took a dump.

Was thinking that too but I put a new clutch on right before I charged it the second time. I’ve verified it works and the fan howls now. The ambient was about 90 degrees when this happened. Radiator and condenser are not plugged air flow wise.

 

[Poppy 87]

Hunter, there is most likely a restriction, probably the condenser, and by that I mean internally not airflow across the coils

 

[bucket]

Yeah, something is up. With normal operation, there should not be any reason for the pressure to climb that high.