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Discussion Starter · #1 ·
I replaced my battery yesterday, and now my a/c only blows air out of the defroster, the floor vents, and the backseat vents. Nothing comes out of the dash.

I have read that the pcm needs to be reset and I have tried to reset it. I have tried disconnecting the negative on the battery for 10 minutes, then letting the truck run for ten minutes, and it didn't work.

I also tried to disconnect the negative, and then turn the key to run, and I let it sit for 90 seconds, and that didn't work either.

I don't know what else to try, if anybody has any other ideas I would greatly appreciate it !!
 

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Discussion Starter · #3 ·
Thanks !!

Ahhh. Thank you. I have looked at some of the threads with concerning this problem. I guess I need to start researching prices for a new mode door actuator. I'm hoping I can do this install. I installed the head unit in my truck, I'm guessing this is going to be a bit tougher though...
 

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2005 chevy trailblazer_ls_ext
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I replaced my battery yesterday, and now my a/c only blows air out of the defroster, the floor vents, and the backseat vents. Nothing comes out of the dash.

I have read that the pcm needs to be reset and I have tried to reset it. I have tried disconnecting the negative on the battery for 10 minutes, then letting the truck run for ten minutes, and it didn't work.

I also tried to disconnect the negative, and then turn the key to run, and I let it sit for 90 seconds, and that didn't work either.

I don't know what else to try, if anybody has any other ideas I would greatly appreciate it !!
Here is how I do it. First turn the fan to off (this probably doesn't make any difference but I do it anyhow). I turn the controls (mine are manual) to the vent position.
Then I reconnect the battery. Turn the key to on but do not start the engine. I wait until the clock displays at least 12:03 (it resets to 12:00 when it loses power).
If all your windows are up and you have decent hearing - you can hear all the doors open and close. I'm not sure 90 seconds is quite long enough.

The first time this happened to me was when I changed the battery, and my problem was the rear vents would not blow air out of the vents.
I've disconnected the battery 2 or 3 times since then, and as long as I am patient and remember this procedure - everything works fine.
 

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2002 chevy trailblazer_lt_ext
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Here is how I do it. First turn the fan to off (this probably doesn't make any difference but I do it anyhow). I turn the controls (mine are manual) to the vent position.
Then I reconnect the battery. Turn the key to on but do not start the engine. I wait until the clock displays at least 12:03 (it resets to 12:00 when it loses power).
If all your windows are up and you have decent hearing - you can hear all the doors open and close. I'm not sure 90 seconds is quite long enough.

The first time this happened to me was when I changed the battery, and my problem was the rear vents would not blow air out of the vents.
I've disconnected the battery 2 or 3 times since then, and as long as I am patient and remember this procedure - everything works fine.
:iagree: I did the battery disconnect three times and it didn't work- I set the HVAC controls as Super 88 described and it worked.
 
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