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: 117,811 (2,010–311,149)
89 people reported this problem
1999 GMC Sierra 1500 164,322 mi, Visitor
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!
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 1500 127,000 mi, Visitor
System won't deliver to air flow to the proper place, ie defrost,floor,or ac vents.
1999 GMC Sierra 1500 78,067 mi, Visitor
A/C works great but won't change to heat when required.
2001 GMC Sierra 1500 75,000 mi, Visitor
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
2000 GMC Sierra 1500 210,000 mi, Visitor
system won't deliver to air flow to the proper place, ie defrost,floor,or ac vents.
2004 GMC Sierra 1500 113,254 mi, Visitor
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.
2001 GMC Sierra 1500 151,000 mi, Visitor
Heat vent operation will only blow on the floor and windshield defrost. Does not change position when the nob is turned.
2001 GMC Sierra 1500 195,450 mi, Visitor
Turn on heater and it only blows cold air
2011 GMC Sierra 1500 90,500 mi, Visitor
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 1500 120,000 mi, Visitor
Air will be blowing cold and then just start blowing hot. Switching the truck off and back on usually helps.
2004 GMC Sierra 1500 114,000 mi, Visitor
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.
2003 GMC Sierra 1500 63,000 mi, Visitor
heat only at 90 deg.
2000 GMC Sierra 1500 145,000 mi, Visitor
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 1500 200,000 mi, Visitor
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
the air flow for both hot and cold only goes to the feet and the defrost
2000 GMC Sierra 1500 199,589 mi, Visitor
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
1999 GMC Sierra 1500 150,000 mi, Visitor
Won't switch from,cold to hot, stays on air conditioner all the time, won't switch to heat, replaced the blend door actuator and it still does it. What else could be wrong?
2004 GMC Sierra 1500 60,000 mi, Visitor
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.
Passenger blows. Cold driver side blows hot