replaced batery and air does not come out the vents


Asked by Jun 24, 2008 at 11:09 PM about the 2004 Chevrolet TrailBlazer

Question type: Maintenance & Repair

i replaced the battery and the ac air does not come out the vents

11 Answers


when loss of power to hvac unit sometime the hvac actuators need to be recalibrated. possibly try to remove the hvac control fuse under the driver rear middle seat for a minute and reinstall, turn key on and do not touch any hvac module buttons for another minute to allow actuator to recalibrate then recheck to see if repaired. if that does not fix it you will need to take it to a gm dealer to get it recalibrated with the tech 2 scan tool.

20 out of 20 people think this is helpful.

had battery replaced same issue removed HVAC fuse # 39 under rear seat waited 1 minute then replaced fuse Turn on ignition do not start engine. Wait 2 minutes then start this will recalibrate the actuators I got this from one of the web sites it worked just fine. All vents work correctly now.

32 out of 32 people think this is helpful.

I tried the all the above and still it did not work

17 out of 17 people think this is helpful.

Never heard of a driver rear middle seat.....??????

2 out of 2 people think this is helpful.

Cant even get under the rear seat. Where is the fuse?

8 out of 8 people think this is helpful.

Did exactly what was suggested by Daniel and ageary63 below for my 2004 Chevy Trailblazer. Removed the fuses (#36 and #39)and then re-inserted them after waiting about a minute. After re-insertion, turned ignition but did NOT start the engine. Heard the calibration take place behind the A/C controller for about a minute. Once it was quieted, started the ignition and the A/C was working perfectly again!! This fix probably saved me over $400.00 in unnecessary mechanic repairs. This all started because I had disconnected the batter in order to tighten the battery cable connections which caused my battery to drain regularly. God bless all of you with your help and good advice!

1 out of 1 people think this is helpful.

Cayenne_41435353 I took a look under my rear seat just yesterday because my radio stopped working pulled out some of the fuses tested them then I put them back now my radio works and climate control stopped working???


Would not know how to help as I am not a mechanic nor a car specialist. I simply followed the advice of previous writers regarding A/C. However, try You Tube and put in precisely the problem (e.g., "climate control not working in Chevy XXX") and Im certain you will find some do-it-yourself videos that could fix the problem. Sorry that I cannot help you directly but try You Tube.

10 This is the video for the steps above. Trying these steps now. My 2006 trailblazer will not blow out of the bottom vents after replacing the battery.

1 out of 1 people think this is helpful.

I had to get more creative to get my controller to reset. I had already had a problem with the driver side blowing hot all the time while the passenger side blew cool. This was solved by changing the left temp actuator door. When I changed the door I noticed the new door was in the neutral (middle) position compared to the right door which was all the way open. When I reconnected the battery the AC controller recalibrated itself and everything worked fine. Later I replaced the car's (05 Trailblazer) battery and the top vents quit working. According to the schematics I had, this was due to the mode control door not working right. The air would come out of the top vents when I started the car, but it would start clicking then the top vents would close and all the air would come out the floor vents. I tried resetting it like it says to in SB 07-01-39-007A by pulling HVAC1 fuse for 5 minutes, putting it back in then turning ignition on for 90 seconds. It would not reset. When I turned the car back on it worked for a few seconds, started clicking, then started coming out the floor vents only. I thought maybe the controller couldn't calibrate unless the door started out in the neutral position. I counted the clicks until the door stopped moving (49). I turned it off, turned it back on again, waited until it started clicking and then pulled the fuse when it got to 25 clicks. Waited 5 minutes. Turned car to on for 90 seconds. Started car and everything worked. Not sure if this will work for everyone. Hope it helps some of you. GM knows they made a bad system. They just don't care enough to fix it.

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