The low-pressure switch for the air conditioning? If "yes", this is a bad idea as it will run the compressor continuously while the control is calling for it . . . as opposed to allowing the compressor to cycle as needed to maintain the refrigerant pressure range. It'* okay to do this as a test with the hood open to diagnose stuff . . .

. . . but not for driving around for days.

If the compressor was old/tired/marginal/etc. it may be toast now. Again, need to know for sure what was bypassed.

Let'* get our other questions answered first so we can find the problem. There are a number of questions stacking up, now including mine above.

Cathedral, I agree....

The low pressure switch should not be bypassed for any length of time, only for quick test purposes.......

And yes, we have asked many questions without results.....

Anyone with a Tech II and a set of gages should be able to easily diagnose this problem, by monitoring the gages and the data from the pressure sensor(not the low pressure switch), and if the control head is sending an a/c "request' to the PCM to ground the a/c clutch relay....also there may be control head "B" codes....

he bypassed the low pressure switch for the ac, Ihave re connected it ince you sent me your note, I have cooling right now. I don't drive the truckmuch but when
I do it will cool for a while then it will start to blow warm air. IF i LET THE TRUCK SET FOR A COUPLE OF HOURS AND START IT UP I WILL GET COOLING, HE HAS NOT GOTTEN ANY CODE TO DIRECT HIM TO THE PROBLEm. HE SAID WHEN IT IS COOLING HE CAN't diagnose even when he puts it on the AC machine. Everything checks out ok.
All preasures are fine. we are Baffled. Thanks for all your help

Did he ever have the vehicle when it wasn't cooling? If yes, then he doesn't know what he is doing....

No. Every time I get there the truck is blowing cold air. I drove it today and had no problem with the ac.

If you come to a stop and let it idle with the AC on, does a puddle of clear water start forming under the car? . . . usually behind the passenger-side front tire?

. . . ?

. . . ?

. . . ? One should be cold and one should be warm.

Water runs out like a garden hose