GMC Repair: 2003 GMC Yukon XL - A/C problem, gmc yukon xl, 2003 gmc yukon xl

Question
QUESTION: The air won't blow out of the vents. It will only blow out of the top of the dashboard from the defrost vent and also out of the vents in the back of the vehicle. My husband is pretty saavy at repairing vehicles, but he is stumped.

My husband said, "The vent register motor actuates the door so that the air blows from the dashboard registers. Upon fully opening, the motor clicks on the door gear five times, like it is not stopping. After that, the register motor then reverses and opens the damper for it to blow out of the defroster vent. Don't know if it is the motor control or if it is in the thermostat control switch unit."

Any help you can provide would be greatly appreciated.

ANSWER: Hi
Need question answered first for proper diagnosis.
Is this automatic air?
(in glove box there is a lable[sticker] with all the RPO codes listed. I need the one that says either CJ2 or CJ3)
Thanks
Will wait for reply.Pawl


---------- FOLLOW-UP ----------

QUESTION: Automatic air
CJ2

Thanks!
Pam

Answer
Hi
There is 3 different (possible) fixes for this concern on this year vehicle.
1) The HVAC actuator harness damage.
The damage occurs to the harness where the harness passes between the GLOVE BOX (instrument panel compartment)and the HVAC case. There is some exposed sharp metal at that location and the harness can rub through causing this concern. Open the glove box door FULLY (pass the catches) and you should be able to examine the harness and see damage IF ANY. It MAY not be damaged so...
2)Check on the PASSENGER side instrument panel junction block. If you remove the passenger side IP closeout panel (panel accessible when door is opened) You'll see about 6 connectors. With key off, unplug them, visually check individual terminals. If any seem VERY loose or pushed in too far, repair as necessary.....
3)If all that seems OK, then it will be the Mode door actuator. It is located on the drivers side underdash.
It is rather diffucult to replace. If it gets to the point that the actuator is determined to be the problem, follow post back and I'll send the service information on the procedure to replace actuator.
Hope this all helps
If more assistance is needed, follow post back.
Good Luck
Pawl