Chevrolet TrailBlazer Heating Ventilation Air Conditioning

rsugarekrsugarek Member Posts: 2
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 Member 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!!
  • janie1983janie1983 Member Posts: 2
    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 Member 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 Member 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 Member 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 Member 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 Member 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 Member 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.
  • blazer6973547blazer6973547 Member Posts: 24
    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 Member Posts: 2
    No earthly idea. My rear unit works just fine. Good luck with that one. I appreciate the info for the front unit.
  • blazer6973547blazer6973547 Member Posts: 24
    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 Member 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 Member 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 Member 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 Member 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?
  • bowtieguy1bowtieguy1 Member Posts: 1
    My AC blower went out in the front the back is running just fine no fuses out need help
  • blazer6973547blazer6973547 Member Posts: 24
    there is a relay attached to the blower motor located behind the glove box
  • stevejanstevejan Member Posts: 1
    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
  • robybrobyb Member Posts: 1
    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?
  • pete99bpete99b Member Posts: 1
    i have the same problem only number 4 works
    how did you fix yours
  • lecantorichlecantorich Member Posts: 1
    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?
  • jimbo10494jimbo10494 Member Posts: 1
    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?
  • kmckittrickkmckittrick Member Posts: 1
    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 Member 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 Member 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 Member 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 Member 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 Member 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 Member 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
  • tigartigar Member Posts: 1
    I have an 06 trailblazer that the air works sometiomes usually when it's cooler. Other times the compressor is running but no air/blower at idle, when I start moving I get cold air sometimes but not maybe as powerful as it should be. When I stop at a light it stops again. Not related I don't think but I have replaced the mass airflow sensor and O2 sensor recently ( lean condition in bank one). Thought it might be a vacuum leak or hi speed blower relay. Any ideas ite 90 dewgrees here and need the air fulltime.
  • scott198scott198 Member Posts: 1

    I have a 2006 Chevy Trailblazer, I replaced the battery and now the AC will not blow cool air. I checked all the fuses is there something that I am missing?

    The Air is blowing, and when I push the AC button it lights up, but no cool air.

    Any Ideals

  • bigred29bigred29 Member Posts: 2
    I have a 2003 Chevy TrailBlazer V8. The air condition cuts out every now and then. When it works, it works well, When it cuts out the air is ambient or hotter. I contact a mechanic and they said it is not freon, but maybe the electronically controlled doors in the dash. One door is about $300 and the other is $500. Could it me something else or does sound about right?
  • burdawgburdawg Member Posts: 1,524
    I'd have it looked at for another opinion. When it "cuts out" is the compressor running?
  • bigred29bigred29 Member Posts: 2
    I think the compressor is running. I happens when I am driving so it is hard to tell.
  • jnhnelsonjnhnelson Member Posts: 2
    Blower stopped working but compressor still works fine. Went to install a new blower and found that I had a wiring problem: Burnt ground between motor and resistor. Found several places on the wire that had been hot and had damage but only one place where the wire was burnt in two. I replaced the ground and it lasted for about a week. Question: what is causing the ground wire to get so hot? Any suggestions?
  • walt32walt32 Member Posts: 1
    I have a 05 chevy trail blazer whereby I hear a resonating, tuning folk-like sound coming from the right, passenger side dash of the vehicle. This sound is very low and intermittent. It is heard when the AC is on. The blower blows cold air after about 3 to 5 minutes of being turned on.

    Can anyone help me troubleshoot this problem?


  • blaizer04blaizer04 Member Posts: 1
    a couple of months ago the 5 setting on my air-conditioner and defroster did not work. then all of the sudden it started working. 2 months later i have a horrible smell coming from the vents when i have the heat/defrosters on. it smells like burning plastic or electrical. what would be the cause of this?
  • burdawgburdawg Member Posts: 1,524
    A burned or burning resistor or resistive strip on the blower motor resisitor assembly would be my guess.
  • bigproblems33bigproblems33 Member Posts: 5
    I have an '04 Trailblazer. My #5 setting on my air-conditioner works sometimes and sometimes it don't. Also my air only blows out the defrost vents and the floor vents. Then also when my A/C is on my car has a tremble/idle problem, especially when at a stop light/stop sign. It sometimes turn off. I took my truck in yesterday to an auto shop they could not repair the problem with the #5 setting because it was working at that time so they couldn't diagnose the problem. But the tremble/idle problem they said it the throttle bore that needed cleaning. They said it got coking (not sure if I spelled that right but it sounds like that lol) and that sticks to the throttle bore and it restricts air. And the air blowing out some of the vents problem was due to a bad actuator. They said there were several actuators (IDK) but the actuator in vent for mode applications was bad. Every problem I have had I came on this forum and it shows people entering tons of problem with the same issue. I have even seen reviews from people that has '07 or higher chevy models and they are having these problems and it is ridiculous. I will NEVER buy another chevy/GMC vehicle again. These forums have really helped me to get to the bottom of some of my problems so I could go to a dealership like I know what was going on. But this is ridiculous and chevy does not do a recall on any of this.
  • acso911acso911 Member Posts: 1
    It is probably your after blower. Basically it is a factory default that helps dry our any condensation in you AC vents. It's a good thing, but I think it has contributed to the early demise of my blower resistor.
  • gabby69gabby69 Member Posts: 1
    04 LT electronic AC & Heat controller. Regardless of mode selected air conditioning only comes out floor vents.
  • blazin02blazin02 Member Posts: 1
    We have a 2002 Chevy Trailblazer, we purchased this fresh off the lot in late 2001. We too have had problems, the speakers in the back don't work, the rear defrost has gone out twice. and now our heating and air conditioning blower stopped working 7/11/11. First we lost #1 & #2 in 2004 and a couple of months later we lost #5. So we were left with #3 & #4, well we lost those now too. It seems like this is a common problem. Does anyone have an easy fix for this? :(
  • burdawgburdawg Member Posts: 1,524
    Most likely it's the fan resistor. Have a look at this:
  • bvandebvande Member Posts: 1
    I have a 2009 TB. The amount of cold air coming out declines sugnificantly when the car is running a slow speeds (35 mph or less). However, it seems to produce a fairly good amount of cold air when the car is at 50-60 mph. I also notice a lot of condensation dripping from the metal hose on the left side of the engine compartment under the water resevior when the car is idling in the drive within 30-60 seconds of starting the car. I can't see exactly where the leak is coming from if it is even a ture leak. Before I take it in to a dealer to be ripped, I would like to know if I am look at a major problem or something more common such as a refrigent leak or bad seals. Can anyone give me some advice.
  • snuffalupticussnuffalupticus Member Posts: 2
    not sure about the cold air.. but i had a leak a few months ago... come to find out when you open the hood of your tb look at the left back side theres a rubber 90 degree piece that points down... usually it gets clogged and backs up into the cab.. Pull it off and use a pipe cleaner.. this worked for my 04 trailblazer
  • snuffalupticussnuffalupticus Member Posts: 2
    I have an 04 trailblazer that the rear ac only works on high. sometimes it works and sometimes it dont... And to top it off sometimes it runs when the truck is completely turned off.... How the heck does that happen???
  • randyhayrandyhay Member Posts: 1
    Have a problem that I'm hearing is more common in the 2003 chevy trailbaizer EXT. Both the heat and A/C will now only work on the 5 setting, we noticed ealrier in the summer that occasionaly the air would work only on settings three or higher, however recently the only output we now have is on setting 5. Also with the heat on regardless of the level I now have only cool or cold air being blow into the middel and rear zones. Any ideas or advice would be greatly appreciated, signed desperately seeking heat in cold OK winter.
  • mfowler1mfowler1 Member Posts: 1
    I Just changed my battery in my 2004 LS TB, when I turned on the ignition my AC/Heat only works on defrost vents and a little from the floor vents no matter where I turn the vent control knob. When I key up to accessory I can here something humming or chattering, sounds like coming from top, center of dash. Has anyone experienced this or have any ideas on fix. I appreciate any help you can give me in this matter.
  • pablolpablol Member Posts: 3
    rsugarek said:
    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. Thanks
    Ignition switch, trust me as crazy as it sounds.
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