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2004 gmc: It was sitting for 6 months..truck runs fine

Customer Question
I just replaced the engine...
I just replaced the engine in my 2004 gmc denali xl. It was sitting for 6 months.   Everything went well and the truck runs fine. Since I started it, the HVAC will not blow out the front or floor vents. Only on the windshield as defog/defrost.   A/C and heat are fine but the vents do not seem to respond to the controls.

I also read that I may have to check or clear trouble codes. What reader/scanner would you reccamend I use or purchase.
Submitted: 8 years ago.Category: GM
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Answered in 12 minutes by:
6/18/2010
GM Mechanic: ironmike, ASE Master Tech replied 8 years ago
ironmike
ironmike, ASE Master Tech
Category: GM
Satisfied Customers: 3,452
Experience: 30 years L1, GM certified
Verified

greetings,

there is a bulletin for the actuator harness.You can check for that and I would get the vehicle scanned for codes. I would even try to clear the codes, turn the ignition key on to run and wait 10 seconds and then start(do not adjust a/c, turn on or off)this allows the actuators to recalibrate.

Bulletin No.: 04-01-38-008

Date: June 17, 2004

TECHNICAL

Subject:
HVAC System Cannot be Controlled or Defaults to Defrost Mode (Repair HVAC Actuator Harness)

 

Models:
2003-2005 Cadillac Escalade, Escalade ESV, Escalade EXT
2003-2005 Chevrolet Avalanche, Silverado, Suburban, Tahoe
2003-2005 GMC Sierra, Yukon, Yukon XL

 

Condition

^Some customers may comment that they cannot control the HVAC (heating, ventilation and air conditioning) system. Others may comment that the HVAC system defaults to the Defrost mode.

 

^Technicians may find that the following diagnostic trouble codes have set:

 

^B0229 Recirculation Actuator

 

^B0414 Left Air Temperature Actuator

 

^B0424 Right Air Temperature Actuator

 

^B3770 Mode Actuator Cause

 

The HVAC actuator harness may contact a sharp edge on the instrument panel support brace, causing a rub through condition and a ground out of the actuator control and/or feedback circuits.

let me know what you find

good luck

 

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Customer reply replied 8 years ago

Do I have to get a dealership to scan for codes or can I purchase a spacific unit that will work with my GMC I do all my own work and like to have all the tools necessary to service my vehicles

GM Mechanic: ironmike, ASE Master Tech replied 8 years ago

you can buy one off the internet. I bought a decent one for 68$ like this one

graphic

 

for other make cars I worked on at the Chevrolet dealer. The tech2 and MDI at the dealer is the best but they will charge you. Most parts places will not charge if you want to get it scanned for free. For 2005 and up the scanners need an upgraded module(can system), you should be fine going to a parts place. You might have lost the HVAC programming too and need to reprogram at the dealer. I would try what we have and then think about the dealer.

good luck

 

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