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.
Improper HVAC Temperature and/or Air Delivery Due to Failed Mode Door Actuator on GMC Sierra 2500 HD
Average mileage: 394,892 (17,041–20,000,000)
86 people reported this problem
50 people shared problem details
2003 GMC Sierra 2500 HD67,800Visitor
Air only comes out dash vents. Changing to floor or defrost switch position does not change air flow.
2004 GMC Sierra 2500 HD306,007Visitor
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.
2006 GMC Sierra 2500 HD113,000Visitor
Blows cold air on driver's side and hot air on passenger side. Should heat both sides.
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.
2004 GMC Sierra 2500 HD63,000Visitor
passenger side blows out hot air when should be blowing cold air
2006 GMC Sierra 2500 HD83,000Visitor
When A/C is turned on, occassionally blows hot air instead. Restart of the engine will usually solve the problem.
2006 GMC Sierra 2500 HD205,000Visitor
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.
2001 GMC Sierra 2500 HD115,000Visitor
Poor airflow. Does not transition through upper vents when selected.
2006 GMC Sierra 2500 HD72,566Visitor
heater actuator will not switch to defrost or floor
2004 GMC Sierra 2500 HD90,000Visitor
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.
2009 GMC Sierra 2500 HD40,000Visitor
when heater is on it will throw heat for a while and then starts to throw cold air out the driver side vents. I haven't found the problem yet. Does any one have an idea what to fix? Gary in Springfield W.Va.
2001 GMC Sierra 2500 HD75,000Visitor
air blows from defroster but will not change modes to vents or floor.
2004 GMC Sierra 2500 HD57,300Visitor
hot air drivers side vent
2002 GMC Sierra 2500 HDVisitor
Air transfers good but I only get a little bit of air flow out the dash vents
2004 GMC Sierra 2500 HD524,356Visitor
heater motor will only function on high speed. We put a new control unit in the dash.
2002 GMC Sierra 2500 HD20,000,000Visitor
Same problem mostly, Blows floor and defrost only. No dash, even after a pot hole now.
2005 GMC Sierra 2500 HD180,000Visitor
I've had the AC serviced several times over that past 2 years...compressor replaced, lines cleared, tested for vacuum and recharged...only to have AC blow cold air for a day or two...no leaks found anywhere in the system, but hot air only comes out....
AC stop working altogether however when passenger side temperature adjuster slide all the way down (cold) can hear a clicking sound
2003 GMC Sierra 2500 HD80,000Visitor
Started truck with weak battery and while it did start, several 'beeps' and other electronic noises heard. Replaced battery, then radio would not work. Removed radio from dash and reset all connection plugs and checked fuses. Radio now worked. While driving, switched air flow control from floor to vent... no air. All air stuck to defrost. With engine off, unplug air flow control module, replug in... can hear actuator motor running. Seems to cycle to "an end", then return... motor runs a few seconds, then will not respond to any further commands unless unplugged and replugged.
2004 GMC Sierra 2500 HD70,000Visitor
heat on one side and cold air on the other,
passenger side air is hot no matter where control is set.
Truck recently cut off when making a turn got 2 boost offs and barely made it home, carmd says...
If I have the system on fresh air & moving at about 30+ mph I can feel a/c, heat,defrost... If...
Both driver and passenger dual controls are set at 60 degrees with AC on. Driver side will only...
Where is the charging port for the AC