One or more heater & AC (HVAC) temperature and/or air delivery mode door actuator may fail, resulting in improper temperature or air delivery. If this occurs, fault code(s) should be stored in the HVAC control module which should assist in diagnoses.Google+
Car Problem Reports
GMC Sierra 2500 HD Heating and AC Temperature and Air Delivery Mode Door Actuators May Fail
GMC Sierra 2500 HD Problem
Average Mileage: 107,924 mi (36,000 mi - 306,007 mi)
Visitor, 2003 GMC Sierra 2500 HD, 67,800 mi
Air only comes out dash vents. Changing to floor or defrost switch position does not change air flow.
Visitor, 2004 GMC Sierra 2500 HD, 306,007 mi
With the A/C on, the drivers side turns to high heat at intermittent times. When the mileage was low, I'd find a pot hole or large lane marker and the little jolt would turn off the heat. Now we are at full stop, shut it off, remove the key and restart. I can hear a small "clicking" sound coming from the dash from time to time.
While I love my GMC Duramax, I hate this problem. Any suggestions on a good repair manual that will cover the A/C systems and circuitry.
Visitor, 2006 GMC Sierra 2500 HD, 113,000 mi
Blows cold air on driver's side and hot air on passenger side. Should heat both sides.
Visitor, 2006 GMC Sierra 2500 HD, 83,000 mi
When A/C is turned on, occassionally blows hot air instead. Restart of the engine will usually solve the problem.
Visitor, 2004 GMC Sierra 2500 HD, 63,000 mi
passenger side blows out hot air when should be blowing cold air
I've got a problem I got hot air coming out the vents on the driver side,and cold air on the pass.side that includes when im running the air.
Visitor, 2001 GMC Sierra 2500 HD, 115,000 mi
Poor airflow. Does not transition through upper vents when selected.
Visitor, 2004 GMC Sierra 2500 HD, 90,000 mi
Air won't blow out of the dash vents but the other modes work fine.
Also occasionally blows hot air in A/C mode. Turning off the ignition and restarting corrects the heat issue.
Visitor, 2006 GMC Sierra 2500 HD, 72,566 mi
heater actuator will not switch to defrost or floor
Visitor, 2006 GMC Sierra 2500 HD, 205,000 mi
Bought used and wasn't told of the problem.....didn't need defrost until two days ago (2 months after purchasing)and it's stuck on floor and panel vents. Will not go to floor only, defrost only, or panel vent only.