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HVAC control panel still being goofy

alrock

alrock

El Diablo
Staff member
Messages
10,677
Location
Scottsdale
Had this issue for a long time and it reared its head again. Whenever the truck battery gets disconnected, the temperature dial does not work properly for a few weeks. On full cold it works fine; turn one click towards warm and it goes to full hot. I've done the calibration procedure, replaced both temperature blend actuators and replaced the HVAC control panel. No changes.

So, battery was last disconnected on Friday so I estimate that by mid-November it should be working fine again. :roll:
 
Hunner

Hunner

Well-Known Member
Messages
2,334
Location
Arkansas
I got the bug too now. I picked up some resistors the other day but have not tried to install them in the temp control line yet.
 
Steve #1

Steve #1

Well-Known Member
Messages
534
Location
TEXAS
I thought you were supposed to hit it when it did that to get it working right..... or is that what you do when the lights stop working. Either way, have you tried hitting it?
 
f5moab

f5moab

Mr. Beretta
Messages
2,000
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In hiding.....
alrock said:
Had this issue for a long time and it reared its head again. Whenever the truck battery gets disconnected, the temperature dial does not work properly for a few weeks. On full cold it works fine; turn one click towards warm and it goes to full hot. I've done the calibration procedure, replaced both temperature blend actuators and replaced the HVAC control panel. No changes.

So, battery was last disconnected on Friday so I estimate that by mid-November it should be working fine again. :roll:
Click to expand...

So, the same heat or lack of heat is on both sides of the hump? If so, I can only imagine it being the controller. It should recalibrate every time you disconnect/reconnect the battery.

Hunner....where will you be putting resistors?
 
T

TANDREW

Member
Messages
7
Location
NORTHRIDGE CA.
Mines doing the same thing. have tried the recal, disconnecting the battery, nothing has helped. It's going into the dealer tomorrow.. will let you know what they find. I've been told it may need a new climate control unit.
 
cbetts

cbetts

NERD!!!
Messages
3,188
Location
Rancho Palos Verdes, CA
Thanks for posting this, Alex. Mine has has the same symptom since I cleaned my throttle body about six weeks ago. I have tried the recalibration several times and have the same problem, cold is fine but one click warmer and it is full-on heat. I would like to get this fixed before the run in two weeks, otherwise I will be playing the adjusting game the entire trip over.

Has anybody passed this my Mike at Tustin Hummer?
 
06 H3

06 H3

a.k.a. "The Jackal"
Messages
9,506
Location
Meridian, ID
Let me know what you guys find...mine is doing the same. I tried the recalibration thing once with no luck
 
Hunner

Hunner

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Messages
2,334
Location
Arkansas
f5moab said:
So, the same heat or lack of heat is on both sides of the hump? If so, I can only imagine it being the controller. It should recalibrate every time you disconnect/reconnect the battery.

Hunner....where will you be putting resistors?
Click to expand...

Well my next step before preceding was to contact you!
so here is what I found from GM.

#PIT4704A: HVAC Temperature Goes Full Hot When One Click Off Full Cold - keywords A/C AC actuator air compressor door heat heater mode - (Feb 18, 2010)

Subject:
HVAC Temperature Goes Full Hot When One Click Off Full Cold

Models:
2006-2008 Hummer H3

--------------------------------------------------------------------------------
This PI was superseded to update the Recommendation/Instructions. Please discard PIT4704.
--------------------------------------------------------------------------------

The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.
Condition/Concern:
Some customers may complain that the temperature will go to full hot when they turn the temperature one click off of full cold. The control head is defaulting to Emergency Mode (this provides HOT air for safety reasons which would be available to clear the windshield in Defrost mode). This will happen if the feedback voltage for the air temperature actuators are out of range.
Recommendation/Instructions:
Replace the HVAC control head with part number 25920831.
-----------------------------------------------------------------------
However if I found the right part it is about $250 dollars.
So some more searching I found that this might be a poor man's fix.
This supposedly would get the reference voltage (5 volts?) regulated again if the switch circuitry has failed.
The light blue with black stripe wire, terminal f circuit 1688, on the driver side of the hvac control head needs 68 ohm 1/2 watt resistor installed inline.
What do you think Mr. Wizard??
 
f5moab

f5moab

Mr. Beretta
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2,000
Location
In hiding.....
Hunner said:
Well my next step before preceding was to contact you!
so here is what I found from GM.

#PIT4704A: HVAC Temperature Goes Full Hot When One Click Off Full Cold - keywords A/C AC actuator air compressor door heat heater mode - (Feb 18, 2010)

Subject:
HVAC Temperature Goes Full Hot When One Click Off Full Cold

Models:
2006-2008 Hummer H3

--------------------------------------------------------------------------------
This PI was superseded to update the Recommendation/Instructions. Please discard PIT4704.
--------------------------------------------------------------------------------

The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.
Condition/Concern:
Some customers may complain that the temperature will go to full hot when they turn the temperature one click off of full cold. The control head is defaulting to Emergency Mode (this provides HOT air for safety reasons which would be available to clear the windshield in Defrost mode). This will happen if the feedback voltage for the air temperature actuators are out of range.
Recommendation/Instructions:
Replace the HVAC control head with part number 25920831.
-----------------------------------------------------------------------
However if I found the right part it is about $250 dollars.
So some more searching I found that this might be a poor man's fix.
This supposedly would get the reference voltage (5 volts?) regulated again if the switch circuitry has failed.
The light blue with black stripe wire, terminal f circuit 1688, on the driver side of the hvac control head needs 68 ohm 1/2 watt resistor installed inline.
What do you think Mr. Wizard??
Click to expand...

Never saw that preliminary investigation before. It's interesting, easy to do and you have nothing to lose. I just wonder where they came up with the resistor spec. Evidently, someone already knows what the default reference voltage output is from the controller. I wonder why GM did not authorize a repair. (I say that with sarcasm. Saturn we used to do inline resistor repairs for certain items, but GM very, very seldom would ever do such a thing. Easier for them to just let the customer pay for a new unit. I say that since I bet most will fail after the warranty period.) Yes, GM sucks....

Have you tried it? If so, how did it work out. If not, let us know. Like I said, easy to do and if it works, your info here might save a lot of people a lot of money.
 
Hunner

Hunner

Well-Known Member
Messages
2,334
Location
Arkansas
I was just typing an email to ya and decided to check for a reply and saw your response.
I think I will attempt that today. Hope I don't blow it up! lol

Houston we have cold air! I tried clicks all the way to straight up and down before it warmed up as it should but not full hot as before.
It took longer to get out all the tools and the camera than to fix it. So $.26 for a resistor a piece of scrap shrink wrap, two drops of solder instead of the GM fix of $250+ if you find the control or $400? if a dealer fixes it???
I will post up in the tech section for those that need specifics.
http://www.hummer4x4offroad.com/forum/showthread.php?3962-Climate-Control-fix&p=70886#post70886
7396.jpg
 
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Hunner

Hunner

Well-Known Member
Messages
2,334
Location
Arkansas
Alrock you said you replaced the HVAC panel and that did not fix it? How much was that?
I wonder what the deal is on that if the resistor fixed it?
That sounds like if even a recommended new one did not fix it and the resistor does it must be the output reference voltage from some where else is failing? I wonder it that affects anything else?? I don't have any display warnings or idiot lights on.
F5?
All I know is it worked and I will be out today and will adjust it to different settings to see if this fix continues to work. If not, I got 4 more resistors!

ps I recall a reference voltage on the locker, remember that F5?
 
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alrock

alrock

El Diablo
Staff member
Messages
10,677
Location
Scottsdale
I used a HVAC panel from another H3 that was working properly. I didn't experiment with a new one. First, I did purchase two new actuators and that did not fix it. Second, I replaced the HVAC control panel with a working one from another H3 and that did not cure it either.
 
cbetts

cbetts

NERD!!!
Messages
3,188
Location
Rancho Palos Verdes, CA
I just ordered a new one since the lights are out in mine as well. I am thinking about making the changes internally on the old unit along with light bulb replacement for the next time.
 
T

TANDREW

Member
Messages
7
Location
NORTHRIDGE CA.
Well it cost me over $500 from the dealership. got charged $400 just for the part. New climate control. Should have waited a day i would have tried the resistor fix that Hunner found first.
 
Hunner

Hunner

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2,334
Location
Arkansas
Sorry! I just could not seem to get time to try it any sooner.
So from what you said that did fix it by replacing the entire assembly in your case.
Alrock tried using a replacement that was working in another vehicle, as I understand it and it did not fix his.
What I am wondering was if it was an internal resistor in that head assembly that failed or it was a voltage sent from somewhere else or if in some cases it could be a different cause? hrmmm that's above my pay grade.
I did not remove the entire control assembly and see if I could open it up to see what is in there besides the switches.
I drove 150 miles or so yesterday and it was 82 so I was on cold, but low 60's on the way home and I was still able to adjust the temp, yaaaa
So does that mean I can justify $499.74 credit towards the tires I just bought?:shifty:
 
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T

TANDREW

Member
Messages
7
Location
NORTHRIDGE CA.
Yes works great, have tried it out on all operations. 1click, 2 clicks, ect, air recirculation in side outside everything is good again. I have seen used controls on e-bay for around $100 just don't know how long they'll last. Seems like there are a few going out after 5 maybe 6 years?
 
yellowh3

yellowh3

Active Member
Messages
42
Location
Arizona
This just happened to me today. I will have to give this a try this weekend.
I just did the fan speed fix last week.
Works great.
 
alrock

alrock

El Diablo
Staff member
Messages
10,677
Location
Scottsdale
telemike said:
How do I get the controls out from the dash?

Sent from my A500 using Tapatalk 2
Click to expand...
If you're talking for putting in new lights or a new HVAC control panel:

  1. Put keys in ignition, turn to ON but do not start the truck (if auto shift)
  2. Put shifter in "1" (if automatic)
  3. Place your fingers in the two 12V accessory sockets, pull out and up. May need a bit of tugging the first time you do this
  4. To fully remove the center console: undo the clips from top to bottom for hazards, 4WD control, radio and antenna, HVAC controls, rear wiper, 12V sockets
  5. HVAC control is held in with a few screws
  6. To take apart the HVAC control, it is held together by clips: undo one, put in a wedge (like a paperclip), and move onto the next one. There's about a dozen of them
 
alrock

alrock

El Diablo
Staff member
Messages
10,677
Location
Scottsdale
BTW, put my resistor in today and it looks like it is working properly! Not much room to work in there but the tape that surrounds the wire bundle slid right up the wires and gave me room to cut, strip, bend and solder the wires. Took about 20 minutes.
 
ReconH3

ReconH3

Guardian Angel
Messages
2,288
Location
Raleigh, NC
Amazing simple solution. Thanks so much for finding it, and sharing it. :D

I wonder if one can do this ahead of time to avoid the problem even if it hasn't happened already.



Ex Umbris Venimus
 
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