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  1. #1

    Default Heat while on a/c

    I'm having a problem with the a/c on my '03 Suburban...
    I'll be driving down the road with the a/c blowing just fine, when, all of a sudden, heat will start coming out of the driver's side.(I have the analog dual controls.)
    My only fix has been to pull over, turn off the truck, then turn it back on. This works for 5 min...sometimes 5 hours.

    Anyone know a solution? It's very annoying--especially when it's 100 outside.

    EDIT--forgot to add...
    I've also tries disconnecting the neg. terminal for a few hours to "clear things out" with no luck.
    Last edited by LowcountrySuburban; 08-31-2011 at 05:03 PM.

  2. #2


    It may be a blend door actuator issue. it sounds like you have dual controls. If so i would look more toward the heater control valve. Can you hear your blend door open and shut when you switch from heat to AC? If so then check the control valve.

  3. #3


    it is more than likely the control panel in the dash.If it were the heater control valve clearing the truck by shutting it off taking loose the 'neg' cable would have no effect. The valves are control by the panel.Some are vacuum operated and pull from a common vacuum source,call your dealer..any dealer..and see if there any 'TSB's on the issue your having. T_Tech S_Service B_Bulletin..

  4. #4


    I've had similar problems with my 2004 Silverado.

    Click image for larger version. 

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    For weeks I could hear an actuator (couldn't tell if it was vacuum or electric) somewhere below or behind the glove compartment trying to do something intermittently, often it would go into a mode of trying up to 3 times per second, lasting for a half hour or more. This occurred intermittently for two months, then stopped. Then a couple weeks later, I started noticing that the passenger side always blows hot air, never cold. I'm guessing some actuator was malfunctioning, then finally failed completely, stuck in the HOT position. I can control where the air comes out (floor, in yer face, or up on the dash), but moving the slider controls up or down has no effect on the passenger side temp, even with the AC on or off. The driver side temp is responsive to the controls as it should be, but not the passenger side. I've heard there's a temperature blend valve for each side that responds to the slider temp controls. Does anyone have pictures or a procedure on how to get to the blend valve, or whatever it's really called?

  5. #5


    By the way, I've tried 4 different control panels, all with the same results. My original one had one failed light bulb behind the passenger slider control, so I opened it up to investigate, and destroyed the left slider control when the knob wouldn't come off...swapped out 3 other panels from the junkyard before I found one with all good bulbs, and they all performed the same, so I believe we can rule out the panel..

  6. #6


    I don't have the dual climate controle, but the heat and ac were acting up..... After the easy stuff I think I am going to go after the actuators.... my 2000 has 3 of them.... a temp one, a mod one (no idea) and a third one for the flaps.

    But everytime I work under the glove comp. box ( cabin air filters, etc ) my hands get tore up more than working on the engine....... It would be nice to just pull the hole unit out and the work on it in the garage and then put it back in....

    Is that possible? I think it is like 3-4 bolts right and the hole unit will come out? (well disconnect the power to it)

  7. #7


    Since you have a 2000 without dual climate control, and I have a 2004 with dual climate control, I doubt if we have any parts in common. I'd be very surprised if any useful major assembly could so easily be removed for service on the bench. Most likely, we'll both have to crawl around on our backs under the dash, reaching up and getting all scratched up trying to pull some small actuator out of an impossibe position. Anyone have photos or tutorial on this? By the way, mine is working fine today.....let's see what tomorrow brings.

  8. #8


    With the AC on my 2004 GMC Sierra started blowing hot air on the passenger side while the driver's side blows nice cold air as it should. I read up on this, online, and learned that sometimes disconnecting the battery for 10 mins helps. I did this but it made no difference. I'm pretty convinced a door/damper is stuck in a position it shouldn't be ... but am not sure where to look for the door/damper that'd impact only the vents on the passenger side of the cab.

    Can anyone shed some light on what my next steps should be to troubleshoot and fixing this? Summer's not quite here, yet ... but I need to nail this one before it gets hot, outside.
    Last edited by SurrealOne; 04-09-2012 at 12:24 PM.

  9. #9


    Mine continues to be intermittent.

    Sometimes the passenger vents blow hot air even though the AC is on and both temp sliders are all the way down, and I get cold air on the drivers side. After a few days like this, it will suddenly start working right. It never goes from bad to good while running, it's always after shutting it off and re-starting....haven't noticed how long it needs to be off before re-starting.

    Another wierd mode is that the air comes out by our feet instead of in yer face via the dashboard vents, in spite of the round knob being set to the "in yer face" position. The cold/hot control still works in this mode, and I can get the air coming out at our feet or up the defroster vents up by the windshield, but I can't get the air to come out the dash vents. Here again, after a couple days, this goes away and it works fine.

    Go figger.

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