Could be a few things.
No 12v to the compressor.
A/C clutch coil shot
A/C clutch shot (just had mine replaced last week)
The hissing sound you're talking about is the vacuum. It is a normal sound whether or not the A/C works. The 'A/C switch' determines where the air comes out. It makes that hissing sound no matter what. Run your truck, turn it off and pull the key out. Keep switching the HVAC control switch and as you cycle past vent locations, you'll hear the hissing. Has nothing to do with A/C itself (unless of course the switch itself is bad and preventing 12v to go to the compressor).
No 12v to the compressor.
A/C clutch coil shot
A/C clutch shot (just had mine replaced last week)
The hissing sound you're talking about is the vacuum. It is a normal sound whether or not the A/C works. The 'A/C switch' determines where the air comes out. It makes that hissing sound no matter what. Run your truck, turn it off and pull the key out. Keep switching the HVAC control switch and as you cycle past vent locations, you'll hear the hissing. Has nothing to do with A/C itself (unless of course the switch itself is bad and preventing 12v to go to the compressor).
