I have a 95 GMC Sierra Z-71 with a 5.7 engine I turn the A/C on and it blows hot air like the heater is on. it has plenty of freon the compressor is coming on and the climate control switch is working because I can hear the damper switching when I switch from cold to hot. I can turn the A/C off and I still get hot air coming out. any ideas?

 

Open the hood and look at the A/C compressor; notice that part if it is a clutch and the rest of it is kinda like a flywheel the clutch engages the A/C compressor shaft to. The outer part spins with the belt, but part of it doesn't when the A/C is off. Have someone start the engine with the A/C off, then tell them to turn it on. You should hear the clutch on the front of the compressor engage and notice that before only part of the pulley was spinning and now the whole thing is spinning. It will usually cycle in and out, sometimes more often than others. The key is that the compressor needs to engage...if it isn't, that's your problem.