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 1500
Average mileage: 113,388 (2,010–311,149)
91 people reported this problem
58 people shared problem details
A/C only cold on passenger side. Drivers side blows hot. There is no adjustment on the drivers side for temp. If you turn off the truck and then restart, it might work for a bit or not.
1999 GMC Sierra 1500164,322Visitor
When selecting where i want my air to go, it only comes through the vent at my feet and through the defrost. The dash vents do not blow any air. It seems like a common problem. Im gonna go ahead and replace the mode actuator!
1999 GMC Sierra 1500127,000Visitor
System won't deliver to air flow to the proper place, ie defrost,floor,or ac vents.
2001 GMC Sierra 150075,000Visitor
Can't change heating/a/c temp unless I shut down truck and reset to desired temp and restart, then it goes to correct temp
1999 GMC Sierra 150078,067Visitor
A/C works great but won't change to heat when required.
2000 GMC Sierra 1500210,000Visitor
system won't deliver to air flow to the proper place, ie defrost,floor,or ac vents.
2001 GMC Sierra 1500151,000Visitor
Heat vent operation will only blow on the floor and windshield defrost. Does not change position when the nob is turned.
2004 GMC Sierra 1500113,254Visitor
a/c blows hot driver side/cold passenger side. may start cold both sides then driver side starts blowing hot and getting hotter. passenger side continues to blow cold air. tried recalibration, pulling fuses, restarting, stopping vehicle turning eng off and restarting eng and then a/c same results.
2011 GMC Sierra 150090,500Visitor
Air blows out the vents for about 20 mins, then it starts blowing out slower and soon it is blowing out in the ducts, but not coming out anywhere, (vents, defrost or the feet ) .
2004 GMC Sierra 1500114,000Visitor
This is a well documented problem as you can see by reading articles throughout various internet sites. For being the so called a "Professional Grade", I have had so many problems with my GMC, from the instrument cluster, steering column, bed liner, hubs, ABS, emissions, etc.... and now with the HVAC - I'd give my 2004 GMC Sierra a disappointing "F". GM needs to issue Campaign to correct this problems, since so many of their customers are experience problems due to their poor workmanship or inferior design.
2001 GMC Sierra 1500195,450Visitor
Turn on heater and it only blows cold air
2004 GMC Sierra 1500120,000Visitor
Air will be blowing cold and then just start blowing hot. Switching the truck off and back on usually helps.
2000 GMC Sierra 1500145,000Visitor
textbook problem like all others. Temp. adjuster knob when turned to cold would only blow hot all the time. Actuator is at fault.
2003 GMC Sierra 150063,000Visitor
heat only at 90 deg.
2003 GMC Sierra 1500200,000Visitor
blows out vents and floor only no defrost. previously could here groaning sounds coming from passenger side all the time while driving. took dash apart , flapper behind glovebox swings loose
2002 GMC Sierra 1500125,000Visitor
Same as the below how do I fix it thought I only see the complaints and no solutions
2004 GMC Sierra 150060,000Visitor
I haven't fixed it yet, but when driving with Air conditioning running, just the drivers side gets hot, the passenger side stays cool. I pull over, turn my truck off, then I continue on my way. This happens 3-4 times in a 50 mile trip. I've checked with different places & it will cost anywhere from 200.00 to 600.00 to fix.
2000 GMC Sierra 1500199,589Visitor
i have problems when i u the air or heater.i have to shut the car off for half hour before i can u the other
the air flow for both hot and cold only goes to the feet and the defrost
The airflow adjustment from the defrost to floor to vents does not work
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