Tim wrote:Do you lose air volume when it stops cooling. That heat switch on top of the compressor may not be working correctly. But you need to trace down why it is not cycling.
What are the highest pressure you see, normally right before it stops cooling.
Thanks, Tim. I should have mentioned that the low side psi was STEADY at 45- never fluctuated. That also migh be a key to the mystery (?). I keep hoping for a clue to the mystery. High side barely moved either, but it was a little tricky as when I was in the cab I coudnt see the guages. But to answer your question air volume didnt seem to change- just kept blowing at a good rate.
Know what could be causing the engine to shake to badly?