Good afternoon ! Was driving the truck the other day AC blowing out cold cold air . Parked the car for a few went back and was driving 3 mins and it started to blow warm air . Went from cold to warm in an instant . Its moist and wet feeling when you put your fingers up by the vent . I checked the fuses under the hood nothing seems blown . Can't really see if the black box fuses are blown tho . Is there anywhere else for fuses ? Any ideas what maybe wrong ? Truck has 128k on it and still looks and shines like new no dents or scrapes or scratches . Always serviced like my mechanic says .

 

Sounds like the compressor if it was all the sudden, can you hear the clutch kick on when you engage the a/c? Make sure you didn't hit the ECON button, I've done that on accident and while wondering why my a/c wasn't working.

 

Checked yesterday to see if there was any pressure in the system. There is none in the system . I made sure the Econ button was not on . The compressor seems to be running and the center part seems ingadged on the compressor . I hit the Econ button and the center still spins away . Checked the lines as much as I could see . I live in wa state so no corrosion that can be seen . I guess it's a trip to my mechanic . Does anyone know if it's bad to run the Heating/ cooling with no pressure in the system ?

 

The "center" will always spin. The compressor on our rigs are not of the old type with a clutch that engages the pulley drive. It is of the variable internal valve type, so you can't really tell by looking whether or not the compressor is "engaged".

No pressure, not the compressor. You should at least have some kind of pressure in the lines...even when the vehicle is not running. No pressure is an indication of a sudden leak.

Good luck.