Calling new GM model owners with Dual Climate Control

[Trancer 10+ year member]

Ok, So I was driving on George Bush Tollway last week and noticed my a/c wasnt blowing that ice cold air like usual. It was blowing "cool." Turned the AC button off, blew straight hot air, turned it back on and it was blowing "cool" air. Took it up to Classic in Carrollton where I bought the truck new, from them. Put it on the machine, gave it back to me and said it was in range. Drove home, seemed a little better, but something was still up. Drove today and it was blowing out hot air. I turned off the drivers side vents and stuck my head in the passenger and they are bowing out COLD air. Not its not ICE COLD, but its workable COLD air.

Anyone know whats going on here? Im thinking there is something wrong with the sensor for the drivers side or the vent not fully closing off. I drove home at 2:00 in the morning, at 87*, sweating my *** off in my own truck.

Its a 2008 GMC Sierra Texas Edition Crew Crab SLE2. Just about every option imaginable. One more option and you are a Denali. 46k miles on the truck, 90% highway with my job. I dont get it. Its a new truck. Bout to roll this bish off a cliff and go get me a new 4x4 crew cab turbo diesel.

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[MiX 10+ year member]

Its the actuator. Happened to me before

 

[Mitch86 5,000+ posts]

Its the actuator. Happened to me before

Have this same problem in my Impala and was told it was an actuator also...

 

[Trancer 10+ year member]

Thanks for the help!

 

[thevic24 5,000+ posts]

Blend door actuator for the driver side.

 

[Trancer 10+ year member]

F this. Time to trade the truck in.

 

[thevic24 5,000+ posts]

Here is a service bulletin I found...

Bulletin No.: 07-01-38-009B

Date: November 28, 2007

TECHNICAL

Subject:

EI07264 - Manual HVAC, Temperature or Mode Actuator Performance, A/C Does Not Cool, Unable to Change Mode, DTC B0228, B0413, B0423, B0433, B3779, B3782 (Diagnose for Intermittent Wiring Connection at RH BEC) Models:

2007-2008 Chevrolet Silverado

2007-2008 GMC Sierra Extended and Crew Cab Models Only with Manual Temperature Control HVAC System (RPO C67)

Supercede:

This bulletin is being revised to end the need for engineering information and to provide diagnostic procedures to accurately diagnose this condition. Please discard Corporate Bulletin Number 07-01-38-009A (Section 01 - HVAC).

Condition

This concern only applies to Extended or Crew cab vehicles.

If the customer did not bring their vehicle in for this concern, do no proceed with this bulletin.

Some customers may comment that the A/C blows hot air or is inoperative. They may also comment that they are unable to change the temperature or HVAC mode of the vehicle. Under these conditions, the actuator has moved to a default position. Refer to the table.

Cause

GM Engineering is seeing an increase in HVAC control head and actuator warranty where the component is fully functional when received. The root cause of the failure is intermittent wiring connections at the right hand BEC. Specifically, poor terminal tension of the 5V reference or Low Reference terminals in the X4 connector. Refer to the table.

After the fault is removed. the actuators recover once commanded.

Correction

DO NOT REPLACE THE CONTROL HEAD.

Use the following information to diagnose this condition:

The concern must be current before diagnosis can be performed.

Review and print the following SI documents - Electrical Center Identification Views, for use during diagnosis:

- Junction Block - Right I/P, Top View - Junction Block - Right I/P X4 - Junction Block - Right I/P X5 Locate the Junction Block - Right Side IP on the vehicle.

For the appropriate actuator, measure the following signals for voltage/resistance from the BACK of the X4 or X5 connector and record the following:

DO NOT unplug the X4/X5 connector.

Turn Ignition On, A/C Blower Full, if possible - mode on "panel" and Temp to "cold."

Once the fault is removed, the actuator will stay in default position until commanded to a new position. Change commanded position regularly to see if the issue is still current.

Continue to monitor door positions (feedback) on Tech2 to see if it changes during circuit testing.

- Ignition Voltage - 12V - Door Control Signal - 2.5V when stationary, OV when commanded toward "cold" or "panel", 5V when commanded toward "hot" or "defrost" - Low Reference - less than 40 ohm with ignition on. Less than 10 ohm with ignition off - Door Position Signal - measure voltage - 5 Volt Reference - 5V If any signals do not display the correct value or if the issue is corrected during testing, pull the connector and check the terminal for poor tension (use the appropriate terminal tool). Replace or repair the terminal if poor tension is found.

If all signals are correct at RH BEC, reconfirm the customer's comments.

If the condition is not present, no further repairs are necessary. If the condition is still present, recheck the actuator connector 5 volt reference circuit, pin drag test and repair connector/pin as necessary.

Warranty Information

For vehicles repaired under Enqineerinq direction, use the table.

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