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2004 chevy trailblazer_lt_ext
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Discussion Starter #1
I think I have a gremlin running loose in my dash. First, I have a six month old battery, charging system tested and working fine. My wife was sitting in the car listening to the radio for about one hour while I was in the dentist chair. When I came out and went to start the TB, it was totally dead. Wife said the radio had quit working about 15 minutes before. This thing was so dead that I couldn't even get a single click on the solenoid. After getting a jump, everything is working fine till today. Turned the heater to full upper vent mode, high fan, and all it would do is put heat out the lower vents or the defrosters if I selected it. Fan motor was blowing full, so I think the resistor pack is ok. Now, back to the radio. The dealer changed our radio out two times over three years. The thing would get so hot it was uncomfortable to put your hand on it. This is the third one in there, and it has always gotten hot too. I'm thinking that there was something inside the radio that shorted out the battery causing it to go dead, and also due to the heat, something happened to my vent controls. Has anyone else experience anything like this, or have any ideas?:crazy:
 

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2004 gmc envoy_sle_xl
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The HVAC system lost its calibration when the battery died. In order to recalibrate it, do the following;
Set all HVAC controls and switches to their OFF position or full CCW positions
Disconnect the battery for about 3 - 4 minutes
Reconnect battery, don't move any HVAC controls and start truck
Let it run for about 3 - 4 minutes, then try the HVAC system.
If it still is not functioning correctly, there may be a stuck door or bad actuator.

As far as your hot radio, didn't the dealer investigate why it was getting hot? First thing to do is measure the current the radio is drawing.
 

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2004 chevy trailblazer_lt_ext
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Discussion Starter #3
Thanks Freddyboy61. I just did what you said and its working perfectly. Never thought about the computer controlling the fan modes. Thanks again. As for the radio, i just assume that the dealer checked for current draw. This is the third radio that been in the car now, the dealer replaced both the bad ones under warranty. My daughter has an identical TB and hers has done the same thing. I'm thinking now that I will replace the factory one with one from Crutchfield when i can save enough money. As for the draining of the battery, we just won't use the radio unless the car is running, hopefully that will be a temporary fix. Thanks again.:thumbsup::thx
 

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2004 chevy trailblazer_lt_ext
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Discussion Starter #4
:tiphatHey Freddyboy61, I just noticed that you posted from L.I. Hope your doing alright after Sandy. Best wishes. :tiphat
 

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2004 chevy trailblazer_lt_ext
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Discussion Starter #5
Well, it's broke again. Just went out to go to the store and the heat won't blow out the vent again. I tried another reset by disconnecting the negative on the battery, it didn't work. This time though, the blower isn't going to the highest speed, so I think I may have a blown resistor on the resistor bank. Any ideas ?
 

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2004 chevy trailblazer_lt_ext
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Discussion Starter #6
Well, got it to work again. In the meantime I have ordered the ACDelco 15-73596 Heater and A/C Mode Door Actuator. This time after I got the reset done I listened for the actuators to calibrate themselves, they made alot of clicking, now it works again, but who knows for how long.
 

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2003 chevy trailblazer_ls_ext
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telemaster

Hi everyone. Just joined the site today. Hope someone can tell me the proper way to recalibrate the hvac actuators on my 2003 t/b so the dash vents will work. The wife is driving me crazy to get it fixed. :(
 

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2004 chevy trailblazer_lt_ext
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Discussion Starter #8
This is a quote from Freddyboy, about 5 posts above. It worked great for me.

"The HVAC system lost its calibration when the battery died. In order to recalibrate it, do the following;
Set all HVAC controls and switches to their OFF position or full CCW positions
Disconnect the battery for about 3 - 4 minutes
Reconnect battery, don't move any HVAC controls and start truck
Let it run for about 3 - 4 minutes, then try the HVAC system.
If it still is not functioning correctly, there may be a stuck door or bad actuator."
 

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2003 gmc envoy_sle_xl
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HVAC almost working

I recently replaced my battery and like many others in this forum, suffered the problems of no Blower afterwards. Since it's freezing out, I decided to wait for a break to work on the system, ie calibration, actuators etc...

Yesterday, while idling for an extended period, the blower ramped up to full speed and the vent controls all worked. Air went to windshield, dash and floor as selected. The blower ran at full speed. I drove home thinking all was well.

Today, I started the car and the vent controls seem to work but the blower is barely moving any air, even at full speed.

Any ideas ??

Mike
 

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They light up when the headlights are on as a component of the scramble brightening yet don't work the atmosphere control framework. The circuit in the drivers side inside wire board checked #30, 10Amp IG HAC was seen as blown and blows each time it is supplanted. Not certain if there is a short in the atmosphere control module for sure yet trusted another person previously handled this and has an answer. Much appreciated such a lot of new companions!
Kodi Lucky Patcher nox
 

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The blower resistor can overheat the battery B+ lug on the board pins. I've experienced this on a bunch of post-2000 models all over the GM lineup.

Calling for Hi Blower, puts a serious amps-load on the pins on the multi connex, and it appears to me that there is a decidedly much more narrow electrical trace on the PCB at that high current spot.

Now...... I'm not accusing GM of deliberately sabotaging these units, but until I hear that there's a designed-in purpose for creating this electrical bottleneck in the board to cause it to prematurely fail... well, my jury's out for more evidence.

Everyone knows that as the blower (normally) gets older and draws a little more current.... that a circuit board running at it's 100% capacity at normal Hi Blower, will probably fail when asked to do so when these normal motor efficiency losses occur. You can't squeeze more power through a junction that's already running at full power.

The dilithium crystals can't take it!

That this is or might be another nasty way for a dealership to sell blower motors and circuit boards (as a pair) plus the labor charges.... to me seems incredulous.

I mean.... c'mon.... how many times has anyone ever seen a blower motor catch on fire? I'm going for ZERO TIMES here! They usually fail as the bearings dry out or someone drops a cool refreshing liquid into them via the defrosting vents.

But... most times, a pending bearing failure makes a lot of noise. The original blower in my'86 K5 has been screaming for 25 years now, and swear I'll replace it when this Corona Virus thing is over.... I swear I will! (maybe)

I've completely decompiled three of these resistor bank units so far..... other times I've just replaced them.
  • This is usually one of those times where I use third party resistor boards. They don't have that very narrow etched trace on the PCB like GM OE... they use a jumper wire of considerably much higher current capacity. Can you say Dorman?
My guess is that a reputable third-party manufacturer, who hates sending out free-warranteed replacements, has a lot of reputation to establish, considering that OE parts are thought of as better all-the-time.

T'aint necessarily so!
 
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