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2003 chevy trailblazer_ltz
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Discussion Starter · #1 ·
My Trailblazer LTZ's rear radio nor a/c will come on. The rear consoles unit lights come on but there is not functionality besides that. Does anyone know what else it could be besides a complete unit failure? The unit is easy to get out so I would like to replace it if that is the most logical failure. If it is the unit that is a failure does anyone know the official name for the rear console "command unit" that controls a/c and radio ? I've searched this forum and googled it and cant find much information...
 

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2004 gmc
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It doesn't fail that often, so that's why there's a lack of discussion. Please fill out your profile so we can tell better what you have. Long wheelbase EXTs are different from the SWB, and I think LTZ has digital HVAC controls, but I have an Envoy so I'm more familiar with their option packages.

If you have digital controls, there is a fuse (HVAC-B - rear fuse block #36) that may be involved.

GM calls it the HVAC control module - Auxiliary. I see them on Ebay all the time for relatively cheap, and sometimes they just call it the Rear heater module or something similar. I can get you the exact part number if you confirm what wheelbase you have and what kind of HVAC system (analog or digital) is involved.
 

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2003 chevy trailblazer_ltz
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7 Posts
Discussion Starter · #3 ·
It doesn't fail that often, so that's why there's a lack of discussion. Please fill out your profile so we can tell better what you have. Long wheelbase EXTs are different from the SWB, and I think LTZ has digital HVAC controls, but I have an Envoy so I'm more familiar with their option packages.

If you have digital controls, there is a fuse (HVAC-B - rear fuse block #36) that may be involved.

GM calls it the HVAC control module - Auxiliary. I see them on Ebay all the time for relatively cheap, and sometimes they just call it the Rear heater module or something similar. I can get you the exact part number if you confirm what wheelbase you have and what kind of HVAC system (analog or digital) is involved.

Thanks! I have a V6 2003 short wheel base LTZ. It has a digital controlled audio and HVAC system in the center console. I checked the fuse and it appears to be ok. The button illuminations show up but the air and the radio dont work..Its kind of odd because you would think if the unit was going to die the lights wouldnt power on as well.
 

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2002 gmc envoy_slt
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3,203 Posts
Just to rule out the simple things......the front HVAC is on and NOT in defrost mode, right? (In defrost mode, the rear controls become inoperative). The rear radio controls can also be locked out to prevent kids from playing around with them. (I seem to recall pressing and holding the 4 & 6 memory buttons together, but its been a while since I looked at that portion of the manual).
 

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2003 chevy trailblazer_ltz
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7 Posts
Discussion Starter · #5 ·
Just to rule out the simple things......the front HVAC is on and NOT in defrost mode, right? (In defrost mode, the rear controls become inoperative). The rear radio controls can also be locked out to prevent kids from playing around with them. (I seem to recall pressing and holding the 4 & 6 memory buttons together, but its been a while since I looked at that portion of the manual).


I have fooled with it a good bit and put the front HVAC on every setting I can find..No luck getting anything on in the rear with any setting in the front.
 

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2004 gmc
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The lights are fed directly from a dimmable lamp bus, and not by way of the module power. You should check the orange wire when you pull it out just to make sure has 12V.

Anyway I don't see one cheaply on Ebay today. That's unusual.

ACDelco 15-72903 GM #15082687
$250 or so at parts4chevys.com and other places.

 
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