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Chevrolet TrailBlazer Heating Ventilation Air Conditioning



  • 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: 4,001
    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: 4,001
    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 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 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

  • 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 Posts: 1,524
    I'd have it looked at for another opinion. When it "cuts out" is the compressor running?
  • I think the compressor is running. I happens when I am driving so it is hard to tell.
  • 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?
  • 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?


  • 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 Posts: 1,524
    A burned or burning resistor or resistive strip on the blower motor resisitor assembly would be my guess.
  • 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.
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