I have a 2001 3500 van and the ac only works when the van is cold ?? Checked High & Low switches both good....checked Freon....checked compressor all are good, Oh and clutch is also good. I noticed that when van gets up @ operating temp that the High press.. switch is getting 12v on both ends of the connector when it is unplugged from switch ?? Does this make sence ?? Also noticed that I get codes POO31-POO37-P1765 & P1495 when van get warmed up.........would this affect AC ?

 

By only works when cold, are you referring to the clutch only engaging when it's cold outside, or when the engine is cold?

You cannot have 12v on both sides of the HPS connector when it's unplugged. One side yes, but the other side goes to the clutch and ultimately ground. Tell us how you're connecting your meter and testing.

Those trouble codes have nothing to do with the A/C system and are unrelated.

 

I was getting 12v to the HPS when it was unplugged ! One lead of the meter was to ground on Batt.. and other was to HPS connector. I think that I found the problem though, it was in the LPS ! one of the wires had an internal brake. I cut bad part out and respliced, all seem's to be working now. Oh, with that one wire fixed I now have 12v on the one side of the HPS.