Truck runs fine until I turn A/C or Defrost on. As long as I keep foot on gas it will run, if I come to a stop it will stall and shut down. Turn A/C off it will start right up
engine stalls with A/C on on 2004 GMC Envoy
Sounds like the idle speed is too low when the a/c compressor is on. The system should raise the idle speed a bit to compensate for the additional load of the compressor, but it doesn't appear to be. There can be many reasons for this and without running some tests and checking it out I would only by guessing. Best to have a shop that can properly diagnose this look at it.
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motor stalls when deforster is slected
it sounds like your throttle body is dirty and or built up with carbon i would try to clean that using a carb cleaner