I just got my A/C serviced and it seems to kick out cold all the time when not towing. When towing a load, I would get cold air for awhile and then it would get warm and then get cold again. There was no consistancy of whether I was going up hill or not. Sometimes it would be cold going up hills and warm going down. Sometimes it would be cold then warm on flat. My ECT running 180-200degrees. I have clutch fan that kicks in at lower temps (165degrees). It appears that the compressor is maybe cycling. Any suggestions to fix this problem.

Sounds like they didn't fill the system up all the way and the pressure is dropping and disengaging the clutch.

Very interesting problem. I wonder, does the computer kill the compressor at WOT/high loads? I had an Oldsmoblie that did that. Go to the floor, and it killed the a/c.

knkreb, thats did cross my mind at the time, but going down hill without I still was getting cold and warm air at different times.

ONLY in towing? Or, was it one time when towing? Seems odd. Maybe a lag time in a/c recovering temperature. You may have cold air for a little while on the ascent, and then it takes a bit to cool back down again on the descent. Just a theory.

Year on your truck?

sounds like while towing you are gettin high condenser temp which results in high head pressure which shuts off compressor on high pressure switch. if anything too much freon will make this worse. Make sure fan clutch is locking good. also take top half of fan shroud off and blow the s*** out of there. I have to clean mine every couple months.
Justin

I took the truck back to the shop this AM and they found that one of the connections on the compressor was loose. They tightened it up and said everything test out good. I won't know for sure until I tow agian on Thurs.