high pressure swith

[lindbergh]

About a year ago or so my fans failed (all fixed now) with the a/c on and the car idling. The high pressure port opened dumping the pressure (and the refrigerant with it). So my question is, is there any adjustment to the high pressure switch so that it will shut off the compressor before the port opens? If not should I replace the high pressure switch, and lastly does replacing the high pressure switch require evacuating the system? I know the low pressure switch does not but am not sure about the high pressure switch.

BTW I am running R-134a - every component was replaced. (compressor, hoses, evaporator, condenser, orifice tube, accumulator and hub assembly including pressure switches).

Thanks.

[David T]

About a year ago or so my fans failed (all fixed now) with the a/c on and the car idling. The high pressure port opened dumping the pressure (and the refrigerant with it). So my question is, is there any adjustment to the high pressure switch so that it will shut off the compressor before the port opens? If not should I replace the high pressure switch, and lastly does replacing the high pressure switch require evacuating the system? I know the low pressure switch does not but am not sure about the high pressure switch.

BTW I am running R-134a - every component was replaced. (compressor, hoses, evaporator, condenser, orifice tube, accumulator and hub assembly including pressure switches).

Thanks.

You should replace the relief valve and the high pressure switch with the correct ones for running at the higher pressures of -134. Replacing them requires you to remove the refrigerant.

[Bitsyncmaster]

My guess would be the relief opens at 500 PSI and the switch opens at 400 PSI. Does your system even have a high pressure switch? The early VIN cars did not.

[David T]

My guess would be the relief opens at 500 PSI and the switch opens at 400 PSI. Does your system even have a high pressure switch? The early VIN cars did not.

Once you pop the relief valve they get "soft" and can now open at a lower pressure. Even if you had -12 I would recommend replacing the relief valve now. Some cars have the high pressure switch by the accumulator and others have it by the input to the condenser coil. Make sure it is even hooked up.

[lindbergh]

The hub (with the high pressure switch and port) was replaced when the system was overhauled and don't really see a need to replace it again since it is not leaking and am not too worried about it going soft. The system does have a high pressure switch so can I assume the new high pressure switch that was replaced when the system was overhauled is faulty? I did check the circuit and it will cut the compressor when the circuit is open (normally closed). To replace just the hp switch does the system have to be evacuated?

BTW I got the hub with the hp switch already attached (from specialt). Am wondering if maybe a low pressure switch could of wound up on the new hub in which case I would assume would never trigger a compressor cut.

Thanks.