So I recently reinstalled a condenser into the truck, dad is a certified installer or w/e it is, AC blows cold as the arctic. However, we could only get the AC running by bridging a wire on the switch that activates the compressor, so it runs full time. We tried replacing the switch/connected at the dryer (on top) which is where we have the plug bridged, but when we put the new one on, it still wouldnt turn the compressor on even on Max AC setting. Any ideas on why it wouldnt be getting the signal through or why it wouldn't activate it?

 

Pressure is off, new switch was bad as well, or the little doohickey in the switch isn't pressing down on the valve enough to open it, so it thinks pressure is zero.....

 

Odd, it was screwed on plenty well. Not sure how pressure could be off as when it was filled showed exactly where it should be

 

Bad switch?

 

I cant imagine it is, but I'll try a new one on it again when I can. If I just jump it to be always running, the air blows fine and cold very consistently. The old switch would cycle on and off quite often, and so we checked it and it just showed it was a little low, so we filled it to proper and then it wouldnt run at all, so we had to jump it.. Running it that way won't damage anything will it?

 

If that's the low pressure switch, it will only be a problem if your system gets low on charge, and if it does, it'll eat the compressor.

 

I'm not sure if its high or low side, its right on the dryer. So as long as it stays blowing cold, it'll be fine to run it like that until I can track down the issue?

 

I would suspect so. May wanna look in the service manual, verify which switch it is. Just to be safe.

 

Says its the low pressure switch and cycles the compressor clutch to prevent freezing, but maintain low temp. So I'm not sure why it wouldn't at least kick on if it wasn't already cold. It definitely has plenty of refrigerant and oil from when we serviced it, as verified by a number of hours running cold :P

 

Check the terminals on the switch with a multimeter and see if the switch is closed. The switch on the accumulator is the low side pressure.