GMC Repair: gmc envoy 2003, judgment call, gmc envoy

Question
When i turn the A/C on my truck it starts shaking and it tirns off unless i step on the gas it wont go off?

Answer
When the AC pump comes on it puts an additional load on the engine.  There is a throttle adjuster that is supposed to give it a little extra gas when the AC comes on so it won't kill.  That thing may not be working.  Or if there is another problem that affects the idle, like an O2 sensor or EGR valve, then that may be the problem.  If it makes an unusual noise when the AC is turned on, then it could be a bad AC pump that is putting too much of a load on your engine.  You did not tell me the miles on your truck, so I can't make a judgment call on that.  Best of luck to you, and thank you for choosing me.