Improper HVAC Temperature and/or Air Delivery Due to Failed Mode Door Actuator on GMC Sierra 2500 HD

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.

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Average mileage: 394,892 (17,041–20,000,000)
9 model years affected: 2001, 2002, 2003, 2004, more2005, 2006, 2007, 2008, 2009
86 people reported this problem
50 people shared problem details
Air only comes out dash vents. Changing to floor or defrost switch position does not change air flow.
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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.
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Blows cold air on driver's side and hot air on passenger side. Should heat both sides.
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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.
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passenger side blows out hot air when should be blowing cold air
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When A/C is turned on, occassionally blows hot air instead. Restart of the engine will usually solve the problem.
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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.
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Poor airflow. Does not transition through upper vents when selected.
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heater actuator will not switch to defrost or floor
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.
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.
air blows from defroster but will not change modes to vents or floor.
hot air drivers side vent
Air transfers good but I only get a little bit of air flow out the dash vents
heater motor will only function on high speed. We put a new control unit in the dash.
2002 GMC Sierra 2500 HD20,000,000
Same problem mostly, Blows floor and defrost only. No dash, even after a pot hole now.
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 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
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.
heat on one side and cold air on the other,
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