2003 Trailblazer HVAC Schematic

firemancyr

Original poster
Member
Feb 22, 2012
2
I've got a 2003 TB EXT with the typical actuator clicking/non-functioning problems in the rear. I've removed the rear panel to access the actuators, and remembered an old site that had the hvac schematic and part numbers for this truck. I went to that "old" site, and saw that there were issues and our beloved Roadie had moved over here. I was wondering if I could get him or one of you other wonderful tech-heads to repost that schematic so that I can find the part numbers? (The truck now is in the shop to replace the motor mounts, or I'd get them directly off the parts themselves, maybe).

BTW, it's both rear actuators.
 

Blckshdw

Moderator
Nov 20, 2011
10,707
Tampa Bay Area, FL
Here are the part numbers :book: Actuators are the same, hope this helps.

GM: 88892975
AC Delco: 15-72811
 

firemancyr

Original poster
Member
Feb 22, 2012
2
That'd be it! lol. Thank you folks so much. Now if only we could get google to direct folks over here moreso than "that other site" :raspberry:
 

FunkZ

Member
Feb 20, 2013
2
My 02 EXT started clicking at right rear. The rear HVAC control module was previously replaced with a used part. Did the HVAC B fuse reset, then turned key on and listened. I hear actuators going through their test motions, both front and rear. There's no clicking anymore, but it seems there is no actuator noise when adjusting either the rear temperature or the airflow controls. The blower still works fine.

So is the control module failed again? Or is it the actuator? Looking at the diagram, the 88892975 part is used for the temp and airflow, is there one part for both or would I need two of these?
 

The_Roadie

Lifetime VIP Donor
Member
Nov 19, 2011
9,957
Portland, OR
There are two actuators. The designer was just smart and used the same part number in each location. To tell FOR SURE if you have a control module, wiring, or actuator problem will require a voltmeter and a bit of electrical troubleshooting experience. Otherwise it's just shotgunning and that can cost you more. Which was do you want to proceed?
 

FunkZ

Member
Feb 20, 2013
2
Thanks for the reply! I went back to the other site and found my previous post from 2009 when the rear hvac control panel was replaced, and it seems the symptoms had been the same. (actuators move after a reset but not from the control module) I looked on eBay but can't seem to find any for sale right now. Do you happen to have the GM part # for the rear hvac panel/module? It's the analog system w/o audio control. (3 dials - blower, temp, airflow)
 

mark'stb

Member
Dec 17, 2011
94
Any tricks to holding door #36 so #33 actuator can be installed? See post #4 for the picture. It just rotates counterclockwise just enough that I can't align the splines. If I eyeball the alignment, the actuator hits the case before it goes in far enough to engage the splines.
 

mark'stb

Member
Dec 17, 2011
94
Figured it out. Drilled a 1/8" hole in the case and bent a piece of coat hanger, stuck it in the hole to hold the door up and the actuator slid tight on,
 

mrrsm

Lifetime VIP Donor
Supporting Donor
Member
Oct 22, 2015
7,985
Tampa Bay Area
Some belated Blend Door Imagery and Positional Part Numbering:

2013-09-02_231701_2004_actuator_2.pngallactuators.jpgnew-blend-door-actuator.jpgoriginal.jpg
 

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