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Chevrolet TrailBlazer Heating Ventilation Air Conditioning

hot air blows out of the drivers side and cold air blows out of the passenger side. It does this no matter where the temperture is set on the drivers side. I heard about another one that was doing this and all they did was turn off the car and then restart it and it started working again. I tried this and it still blows hot air out the drivers side with the AC set to high.
Any suggestions.


  • ticadooticadoo Posts: 40
    I just purchased 2003 Trailblazer and am having the same problem. Any help would be greatly appreciated!!! Mine has been in shop for over a week!!
  • i just bought a 2002 tb im having the same problem hot air comes out no matter what even if i have everythiing turned off....what can i do..?
  • rsugarekrsugarek Posts: 2
    I took it to the dealer and paid them $100.00 to diagnose it. They wanted $600.00
    to fix it. So I figured I could do it myself, I am a pretty good mechanic. I took the dash, center console, everything there was to take off where the blower compartment is. I still could not get to the part that I needed to change out. So I put it all back together a weekend wasted. I then took it to a local shop here by where I work that we take our company trucks to get worked on. They seem to be pretty good. I told them what it was doing and he said oh yeah that it the heater control flap, or something like that. He said that is a common problem on this vehicle. Worst case scenario it will take 4 hours to fix. I already had the part and he said he could just use it. $240.00 for labor later and it is working fine.
    The GM part # is:
    ACDelco part # is:
    Do a search online and you can get it for around $80.00, or from the dealer for $153.00
    I would suggest calling some shops and asking them about it and if they say oh yeah that is a common problem then take it to them to get it fixed.
  • ham4ham4 Posts: 1
    I have a 2005 Chevy TB my 1st problem was no dome lights when doors are open, only hot air blows from drivers side, then no air at all. After checking all fuses and reading messages from this site and others I thought it might be a loose or shorted connection. I checking the rear fuse panel when I noticed when I pushed on the carpet to the rear of the panel the dome light came on. I then took the seat out and inspected the fuse panel. The top pan was loose. I tightend the three bolts and all works as advertised. Hope this helps.
  • scarr133scarr133 Posts: 1
    I have an 02 Trailblazer that has the air vents in the roof for the back 2 rows, and since we've had it, they've never worked. The floor vents work fine, but no go on the roof vents. Anyone have a solution for this? Could it just be a fuse or is something more mechanical messed up? Thanks.
  • agilkisonagilkison Posts: 1
    I have the identical situation. An '02 Trailblazer EXT. Original owner. Roof vents worked in the past, but no longer. Floor vents in rear are fine. I've tried all the possible fuses (at least that I can find) and still no luck.

    I've tried some other web sites but found nothing there either. Any suggestions would be much appreciated. Thanks
  • ksangerksanger Posts: 3
    I hope you have better luck than I. The back heater/AC unit is on the passenger side. There is a servo to control heating and cooling, and another to send air to the floor or roof. Plus fuses under the passenger seat on the driver's side. The computer that controls the servos is near the fuse box. My heating and cooling servo ticks, and is stuck, and the servo for the roof doesn't move at all. But worst of all I have leaks in the AC lines going to the rear unit. The lines are $500 each, plus I'm told about $1500 in labor as they are each one piece. I'm hoping we can bypass the rear AC unit. Might fix the servo's so we still have heat.
    I have 78,000 mi. and have replaced a rusted out tranny oil cooler line, a power stearing line, both front wheel bearings, and had to repair a rear tail light housing. I've needed front shocks for the past 20,000 miles. The trucks loaded, with things that are going to break.
  • keith_h1keith_h1 Posts: 2
    Front blower blows sometimes, sometimes not. Anyone else have this issue? I don't think it would be a fuse because if a fuse was blown, it would never blow. Rear unit works just fine. Is there a control module for the front fan?? I don't want to have someone spend hours and hours trying to diagnose it if I can do it myself. Any help would be appreciated.
  • i have 03 tb ext front blower motor only worked on 5... it was the modual conected directly to the blower behind the glove box. easy fix 20 mins. $56 cdn for new part.... i also have a problem with the the vents for the back rows, they only blow cold any ideas?
  • keith_h1keith_h1 Posts: 2
    No earthly idea. My rear unit works just fine. Good luck with that one. I appreciate the info for the front unit.
  • to make things worse, i was trying to figure it out and i get heat in the rear floor ducts but it is only the top that blows only cold
  • tirtlelovetirtlelove Posts: 2
    Anyone know why my 2002 TrailBlazer AC is not getting cold fast enough? I live in FL, so it's crutial that I get this fix as we are already into the high 90's. Our Lexus takes just seconds to cool the car & it's the same year as the TB. The TB takes several minutes. I took it in this past fall to see if it needed freon, but it was full. huh, Help! :confuse:
  • ksangerksanger Posts: 3
    The rear seat floor vents, behind the front seats, are driven from the front passenger controller. The overhead vents, and the rear row vent on the passenger side are driven by the rear controller. To get air conditioning out of the floor vents I believe we must select both foot and shoulder levels.

    The rear controller has two servos, one that selects either heating or air, and one that controls whether the side or top vents are selected. The servos are located with a blower motor behind the passenger rear tire. The controller is under the 2nd row passenger seat along with the fuses.

    Hope this helps.
  • ksangerksanger Posts: 3
    If you have the rear AC unit too, then the AC is going to both the front condensor and the rear condensor and will take a while to have an effect. I have the rear AC in the extended (EXT) version though it no longer works.

    I would make certain that you turn on the rear AC to full cooling through the roof vents in addition to the front. Otherwise by just using the front you're cooling down the rear condensor but not running air through it.
  • burdawgburdawg Posts: 1,524
    If you go back and look at the main Trailblazer thread you'll see posts about this from early on. If the condensor is hot from sitting in the sun, or from a hot engine after you have shut it off and retarted it while it's still hot, the A/C compressor won't come on until some air has passed over the condensor to cool it down. Add to this the fact that Trailblazers have a viscous controlled cooling fan that runs very slow until the cooling system needs more air pulled over the radiator.
    When we go to our home in Arizona with our 02 Trailblazer we notice this quite often in the summer. If it's retarted while still warm, or if it's been sitting in the sun during the hottest part of the day, it won't come on right away, it usually takes 30 seconds to a minute or so of sustained driving (stop and go makes it longer) until the compressor comes on. If it's been in the garage, even if the air temperature is 110+, it will turn on right away as long as the condensor is not heated up from a hot engine.
    There's no way to change it I'm aware of. Really though, "Our Lexus takes just seconds to cool the car". On a hot day it takes a little longer than that, right?
  • My AC blower went out in the front the back is running just fine no fuses out need help
  • there is a relay attached to the blower motor located behind the glove box
  • I have a 06 TB, 6 cyl., 4WD. After the engine is turned off and key removed and approximately 10 minutes later the front blower will come on and run for about 10 minutes, then turns off. As far as I can tell will not come on again until the key is turned on to run position then to off. This is repeatable.

    I took it to the dealer and they replaced the "body control module" and within two days ( only because I assumed it was fixed) I noticed the blower coming on, same as before.

    Any ideas? Thanks
  • Air Condition not cooling. temp adjustments up or down didn't change temp of air from fan. Checked fuse and relay. This morning the unit started working again? Is there a circuit breaker or auto-reset or is this just one of those "beats me!" situations?
  • i have the same problem only number 4 works
    how did you fix yours
  • My 2004 Trailblazer EXT V6 HVAC mode selection does not change. Currently the blower is only blowing out the floor vents. When I depress the MODE button the display cycles thru the various options. However, the blower only comes out at the floor. When the front defrost is depressed the unit does blow from both the defrost and floor. I checked the fuses and relays. Any ideas?
  • I have a 2007 Trailblazer LT and the mode selector seems to be stuck on the vent position.
    When I select defrost or heat at the feet, a portion of the flow does come put on the selected mode however it never stops coming out of the vent mode.
    Can someone tell me what needs to be replaced?
  • I have an '04 Trailblazer that I bought used with 19,000 miles on it. Over the past year, I started having problems out of it and am slightly disgusted with it. I love my trailblazer but am afraid that Chevy may have produced a few lemons with these vehicles. I had to replace the alternator about a year ago. Less than 2 months later, it had to be replaced again. Then the battery died and had to be replaced. When the battery died, it began a whole new set of problems. My passenger and rear vents will only blow out heat no matter where I set the temperature to on the climate control. If my fuel level gets low enough for the fuel light to come on, within a minute or so the fuel hand will start going back up like I'm pumping gas in to it. The check engine light is constantly coming on and off. If I turn the fan on high, I get a vibration noise. I took it to a dealership when the AC stopped working correctly. I also told them about the other problems I was having. They said that my HVAC control head, blower motor, and passenger side actuator were all bad and needed to be replaced. They charged me $100 to tell me what was wrong and then wanted $2000 to fix it. They still didn't tell me what was causing the rest of the problems. My car isn't worth much more than the AC repair cost at this point. Anyone having any of these problems? Can some of this be fixed on my own? I have a friend who is a mechanic and he said that this wasn't very complicated. He even gave me a printed diagram of where everything is located as far as the AC parts go, but I still have no idea about the other problems. Any suggestions? PLEASE help!!!!
  • roirat96roirat96 Posts: 2
    On my '03 TrailBlazer, the front air quit blowing while the rear air worked fine. The problem tuned out to be a resistor under the front passengers side dash. It cost about $80.00 for the part and .5 hours labor. Basically the problem was caused by a faulty ground within the resistor and if you manually grounded it the AC worked fine. Hope this helps someone!
  • croom43croom43 Posts: 1
    My Trailblazer runs fine until I turn on the AC or Heater... is there something that I can adjust to fix it?
  • jes59jes59 Posts: 1
    edited June 2010
    My Air Condition keeps going out i have to take it to the shop and they have to reboot it in the computer what is the cause of this all wiring checks out
  • gmcustsvcgmcustsvc Posts: 4,252
    Hello Jes59,
    I apologize that you have a concern with your vehicle. Can you please email me with more information about your situation so I can look into this further? You can get my email by clicking on my name. Thank you,
    Mariah GM Customer Service
  • lealajlealaj Posts: 2
    Hi Mariah,
    I have a 2003 Trailblazer and I am having a similar problem. I recently replaced my battery and now the A/C is only blowing at my feet and side vents regardless of the control settings. I see on some postings it is a bad resistor or a faulty ground. Is this something that I can check.
  • gmcustsvcgmcustsvc Posts: 4,252
    Hello Lealaj,
    You can check it yourself or have a service technician look at it for you. Unfortunately I cannot tell you how to fix your vehicle if you are planning on doing it yourself. If you have any further questions please let me know. Thank you,
    Mariah GM Customer Service
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