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HVAC Not Functioning


Charter Member
SM 2004
SM 2003
Full Member
Feb 21, 2002
Greeley, CO
Happened once, but quite annoying. Cold day, cold vehicle - on the road waiting for it to warm up for heat - but the heat never came!

Found that none of the HVAC controls (manual system)were operative except for the fan. The system was 'stuck' blowing cold air out of the defroster. Couldn't direct the air out of the heater or dash vents, couldn't change the temp, couldn't switch from outside air to recirc. (didn't try to turn on the A/C).

Has anyone else experienced this? Any ideas? Until it happens again, I guess I won't worry too much.

Lt. Pewter Z71

Never heard of this problem.

I wonder if there is a loose cable connector or something?
:mad: I had a similiar problem with the half ton Avalanche I use to have. Except the difference is the AC did not work for at least the half hour I drove it. Then later in the day it worked fine and never had that problem again. In a 1999 Silverado ext cab Z71 I had before the half ton Avalanche, The AC went out and then worked fine again and then quit again. Compressor was working and Refrig lines sweating nicely. Thier idea was to change the controls, I recommended they change the damper motor first. The damper motor was the problem here and not the controls.

Tell your dealer to look at the HVAC resistor, sounds like its blown. This should take care of the problem.

Check the thread on "confused comfort controls".
Seems there's a TB on this, some AV's have the wire harness routed incorrectly. My AV is going to the dealer in a few days for this, mine usually sticks blowing heat on a 90 degree day :(