I have a new a/c system on my 97 Ram 1500 but I have a small leak and over 4 months my system got low. I have manifold gauges and was installing more r134a with the low pressure switch jumped. The problem I have is that the compressor will not disengage when appropriate pressures are reached so therefor the pressures keep climbing. When I remove jumper wire and reconnect the low pressure switch the compressor will not engage at all. What is going on here? Thanks! Greg

 

Who installed the new ac system? What all is "new"? Why did you have to install a new system?

 

I installed the new compressor, drier, and orifice tube. I also did a flush and vacuumed it down and it held for half a day. I did the install because the clutch was howling on the oem unit and I opted for a new compressor/drier from NAPA. The new system was installed in late Jan. 2017 and was fine until this past weekend.

 

You evidently have power running thru the circuit.... both switches bad???? Seems unlikely, but, that's where the symptoms are pointing.

 

That 's what I was thinking too but I checked both for continuity and they are fine. ???

 

Check the connectors then.

 

I have jumped the low side pressure switch connector so it has to be good. Would the high side switch/connector have any effect on the low side switch?

 

No. It's a series circuit, BOTH switches have to be closed for the compressor to run. If the low pressure switch tests good, and you also have continuity across the high pressure switch, but, it won't run with the low pressure switch plugged in..... I would still suspect the switch. Continuity is VERY low amperage..... compressor clutch is not. The switch may test fine under no load, but, fail in a loaded condition.

 

I have just noticed the temperature gauge pegs out when the ignition is switched on. Is this related to my ac issue?

 

Does it stay there?

Unlikely it's related. Check the sensor located on the passenger side of the intake, toward the front. (it's on the coolant crossover, near the passenger side head.)