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A/c Only Blow Hot Air After Battery Was Disconnected


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#1 silverteener

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Posted 09 August 2010 - 10:57 AM

Hi guys,

I'm new here and haven't been able to use the search function very well but I have a problem with my 04 GMC Sierra. Last week I had my AC drained and refilled because it wasn't cooling well. While we were doing this we also disconnected the battery for a while to reset the computer because my 4 wheel drive wasn't work properly (another long story). Well once we reconnected the battery and had the AC recharged it now only blows out HOT air. I've read a little bit about how if you disconnect the battery it can mess with your AC but I haven't been able to figure out how to fix it. It goes to the dealership Wednesday but I was hoping to fix it myself. Any advice would be great!

thanks


Scott

#2 snakedoctor

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Posted 09 August 2010 - 11:43 AM

I do not disconnect the battery on my truck ever with the exception of extreme cases, working on the starter, air bag system. If I need to reset something, I pull the fuse to that system. The computer does not need any help learning what ever you did to the truck. The actuator has lost its way. Hopefully after so many cycles it will reprogramme its self. Or you can take the HVAC fuse out for a few minutes put it back in turn the ignition on and then let it go through its programming sequence. Do not touch anything that has to do with the heating AC system while this is happening.

Edited by snakedoctor, 09 August 2010 - 11:48 AM.


#3 USMdude

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Posted 09 August 2010 - 02:18 PM

Blend door relearn. Sounds like your stuck in heat mode.

Jbo

#4 sillyazz

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Posted 09 August 2010 - 02:20 PM

Or try cylcing your key on and off 5 times without starting it.
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#5 redvett

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Posted 09 August 2010 - 02:40 PM

This works for me. Be sure you pull both fuses.

Remove the HV ACIECAS fuse for a minimum of 10 seconds.
Re-install the HVACIECAS fuse.
Start the vehicle.
Wait 40 seconds for the HVAC control module to re-calibrate.
Verify that no DICs have set as current DICs.

#6 silverteener

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Posted 09 August 2010 - 09:37 PM

well guys I tried to reset the system. I first tried turning the key on 5 times and that didn't work. I then pulled all 3 fuses and waited a while. then I put them back in and turned the truck on but did not start it. then I shut it off and got out and closed the door and waited a few more minutes. then I got back in and turned the truck on for a minute or so then started it up. It still blows hot air, no A/C yet. Am I doing the recalibration wrong? I really hate to have to take this to the dealership if it's something I can fix!

thanks

Scott

#7 dlewis1111

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Posted 10 August 2010 - 07:26 AM

Hi guys,

I'm new here and haven't been able to use the search function very well but I have a problem with my 04 GMC Sierra. Last week I had my AC drained and refilled because it wasn't cooling well. While we were doing this we also disconnected the battery for a while to reset the computer because my 4 wheel drive wasn't work properly (another long story). Well once we reconnected the battery and had the AC recharged it now only blows out HOT air. I've read a little bit about how if you disconnect the battery it can mess with your AC but I haven't been able to figure out how to fix it. It goes to the dealership Wednesday but I was hoping to fix it myself. Any advice would be great!

thanks


Scott


Is the compressor kicking on when you turn on the AC? How did they recharge the AC if after re-installing the battery, it wont kick on?

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#8 silverteener

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Posted 10 August 2010 - 08:28 AM

yep,

the compressor and everything on the engine side is working fine. it sweats like crazy!

#9 snakedoctor

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Posted 10 August 2010 - 08:44 AM

Do it your self method..

Remove the HVAC/ECAS fuse for a minimum of 10 seconds.
Install the HVAC/ECAS fuse.
Start the vehicle.
Wait 40 seconds for the HVAC control module to self-calibrate.
Verify that no DTCs have set as current DTCs.

The last time I did this It started working after 5 or 6 drive cycles...


Dealer method...

Start the vehicle.
With the scan tool, initiate the Motor Re-calibration feature of the Heating and Air Conditioning Special Functions menu.
Verify that no DTCs have set as current DTCs.

#10 silverteener

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Posted 10 August 2010 - 09:31 AM

I will try it again today but what are DTC's?? thanks for the help!


Scott

#11 snakedoctor

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Posted 10 August 2010 - 09:39 AM

I will try it again today but what are DTC's?? thanks for the help!


Scott


Thats check engine light codes. They always stick that in the manual.




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