04 TB HVAC issues

IAFF78

Original poster
Member
Dec 29, 2011
205
Good evening all!!

I have a 2004 TB LT and just recently i've been having issues with the HVAC system. The actual system does blow air on all settings. There are times though where i have no air blowing at all. The rear HVAC works just fine. I have no air coming from my floor and front vents. The front defroster vents are the only ones blowing air. I was reading that it could possibly be the blower motor resistor. So i went under the passenger side dash and located the resistor. There are 3 wires( i believe) coming from the unit. When i jiggle the connector, the air starts blowing and all is well but it could go out at any time. The more i read it sounds like the resistor doesnt actually control where the air travels. Any suggestions on what could be going on?

Any and all help is greatly appreciated.

Thanks,
Kev
 
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Capote

Supporting Donor
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Jul 14, 2014
24,227
Atlanta, GA
Hey there Kev, believe it or not this oddly has become a HUGE problem lately for a lot of other members. Lots of threads have been posted about having HVAC problems. I've been helping a lot of others with this stuff. You're right about the blower motor, it doesn't control where the air flows. That is what the "mode valve actuator" controls. It's the center actuator of 3 located behind the dash, but visible from underneath in the footwell. You can see all 3 from down there and to the right. You'll have to remove the tube that directs the air to your feet to properly see them. Here's a picture, to get a better understanding:
Actuators+2.png

The rectangular opening is where that tube is connected at


Do you hear any actuators clicking upon start up?

Here's a link to a recent thread discussing where to locate each actuator and how to go about replacing them:
http://gmtnation.com/forums/index.php?/topic/12766-Replacing-HVAC-Door-Actuator

Another link to someone I was helping today:
http://gmtnation.com/forums/index.php?/topic/12818-I-have-2-questions.-1-is-about-the-vent-doors-and-1-is-about-switches
 

IAFF78

Original poster
Member
Dec 29, 2011
205
I'll have to check on the clicking noises when i get off work in the morning. Thanks for the info. Still trying to figure out if i have a loose wire or faulty connector to the blower fan. Shouldnt just come on/off every time i hit a pot hole...lol


Thanks,
Kevin
 
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Capote

Supporting Donor
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Jul 14, 2014
24,227
Atlanta, GA
No problem, glad I could provide you with some information. That is strange for the blower to behave like that haha, something probably is loose
 

IAFF78

Original poster
Member
Dec 29, 2011
205
I dont know if the terminal is wearing out or there is a short in the wires. I grab the plug and give it a slight wiggle and it comes on. The minute i remove my hand it stops. Weird.
 

Capote

Supporting Donor
Member
Jul 14, 2014
24,227
Atlanta, GA
Hmm I don't really know what that could be for sure [emoji53]
 

IAFF78

Original poster
Member
Dec 29, 2011
205
I'm hoping its just the plug on the motor and not the wiring. :frown:

Thanks,
Kevin
 

IAFF78

Original poster
Member
Dec 29, 2011
205
I just did the HVAC reset. Pulled the HVAC B fuse for 30 sec, replaced. Turned the key to run w/o starting and let it sit for 90+ seconds. I then turned on the hvac and i felt a minor amount of air coming from the front and floor vents. No matter what setting i had selected, 90% of the air was coming out of the front defroster vents. Any ideas on diagnosing this issue further or tests to run to see exactly which parts i need to buy?

Thanks again for everyones help!!

Kevin
 

Capote

Supporting Donor
Member
Jul 14, 2014
24,227
Atlanta, GA
So the HVAC is now running normally bud?
 

IAFF78

Original poster
Member
Dec 29, 2011
205
Not really. Even when the I have the floor vents selected, 95% of the air still comes through the defroster. Just a tiny but comes through the floor vents.
 

Capote

Supporting Donor
Member
Jul 14, 2014
24,227
Atlanta, GA
So the HVAC is working, it's still pushing air, the actuators are what's messed up. On mine, the mode valve actuator is what's the issue. I have air to my feet, but not out the main vents
 

IAFF78

Original poster
Member
Dec 29, 2011
205
I'm guessing that it is the door acuators but not sure which ones are faulty.

After looking at the plug on the wire harness tothe blower motor, I'm thinking i may need to order a new plug and splice it in. If thats the case, where would i find a new plug?

Thanks,
Kevin
 

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IllogicTC

Member
Dec 30, 2013
3,452
IAFF78 said:
I'm guessing that it is the door acuators but not sure which ones are faulty.

After looking at the plug on the wire harness tothe blower motor, I'm thinking i may need to order a new plug and splice it in. If thats the case, where would i find a new plug?

Thanks,
Kevin
I can't see too well, is there corrosion in there or something? In fact, I'm not sure that's the blower motor plug -- it should only be a 2-pin, with a purple and a black wire to it. That right there looks to me like the connector the HVAC Blower Control Module -- a little electronic doo-dad that sits in the airflow path, has the connector running to it from the main controls, and a purple and black wire running out of it to the blower motor.

The blower motor can be accessed (partially) by dropping the glove box.

That 3-pin plug you have in your picture is a 3-Way F Metri-pack 280 Series Flexlock. Original GM part number is 12129489 but I don't seem to have much luck on Google today finding that exact plug.

The 2-pin that's on the actual blower motor is a 2-Way F Metri-Pack 630 Series, Sealed, Pull-to-seat. Original GM part number is 12066681.

These may very well be found at the local Advance/Zone/O'Reilly in the right section, who knows? Not OEM likely, but the proper connectors.

As for the actuators, there's five total up-front:

* Passenger temperature/Driver temperature. These two are self-explanatory.
* Recirculation: This opens up the recirc. You can see the panel it opens up when you drop the glovebox, when OFF the panel will seat over the opening, ON opens it of course.
* Mode Actuator: This operates the floor and vent. Pretty much, pointing one way, it'll go to the floor, pointing the other will go to the vent, and hanging out halfway between does both. When the HVAC system is OFF, it defaults to floor.
* Defrost Actuator: This is likely your culprit. The defrost has its own little special snowflake actuator. Roadie has a picture around here that shows relative locations and part numbers, but if I remember right this is over on the driver's side tucked up in there pretty good. Obviously, it should only open up for DEFROST and DEFROST + FLOOR. Everything else it should be closed.
 
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IAFF78

Original poster
Member
Dec 29, 2011
205
If you're looking at the plug with the clip on top, the left pin connector has some discoloring like it sparked a few times. When I plug the connector in there is alot of play. It doesn't lock in tight like it should.
 

Capote

Supporting Donor
Member
Jul 14, 2014
24,227
Atlanta, GA
Maybe you should go about replacing it if that is the case then, better to be safe than sorry
 

IAFF78

Original poster
Member
Dec 29, 2011
205
I looked at that 3 pin plug that i posted a few weeks ago. The plug is a 3 pin plug with 3 wires connected to it . Its a Delphi plug with a number on it. It's >PA66<

There are 3 wires running to 3 ports and they are labeled A,B and C.
A- RED
B- PURPLE
C- BLACK

Any idea what this plug powers?

Thanks,
Kevin
 

Texan

Member
Jan 14, 2014
622
I would guess that connector is for the HVAC blower motor.
Do you have the manual or automatic control?
If you go to Rock Auto (parts) and look for the blower resistor, you can look
at a picture (info) and compare the connector.
 

IllogicTC

Member
Dec 30, 2013
3,452
Texan said:
I would guess that connector is for the HVAC blower motor.
Do you have the manual or automatic control?
If you go to Rock Auto (parts) and look for the blower resistor, you can look
at a picture (info) and compare the connector.
Motor is 2-wire. I posted above that it appears to be for the HVAC Blower Control Module.
 

Texan

Member
Jan 14, 2014
622
Rock auto shows a 3 port plug for the blower relay.
AC Delco PT756 (GM 12126486). It looks like the one in post #13.
 

IAFF78

Original poster
Member
Dec 29, 2011
205
Well, I order the AC Delco PT756 so wish me luck. Hopefully once i get this sodered in and working(Hopefully!!) i'll tackle my next issue and thats getting the air to blow on the floors and throught the vents.

Thanks,
Kevin
 

Texan

Member
Jan 14, 2014
622
If you look at the post by Steevo , posted today, you may find a
answer to your problem.
 

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