'00 Sierra A/c Blows Cold & Doesn't

[kcarr777]

I have a 2000 GMC Sierra 2500, 6.0 L. The A/C blows perfectly cold and at some point the air will become warm. I can play with the controls (recirc to circ & back, A/C on/off/on) and it will blow cold again. But it keeps going back to warm, till I repeat the cycle. I put on a new "Air Diffuser Door Control" and it had no effect. Just wondering if you might have any suggestions? Thanks, Ken

[wkoerth]

I have a similiar issue. My AC usually works for awhile if I leave the blower control on 2 or 3. If I go higher, the clutch disengages and blows hot air. I have to cut off the air and wait a few minutes and cut it back on to get the AC to work again at low blower levels. It will stop working at lower levels as well but usually will stay on longer. I replace the pressure switch, but that didn't help. Not sure what else to try.