Rick's Free Auto Repair Advice

Air only blows through defrost vents

Air only blows through defrost vents

Air only blows through defrost vents, cannot change heater settings, Escalade, Avalanche, Silverado, Suburban, Tahoe, Yukon, TSB, #04-01-38-008

GM has issued a technical service bulletin (TSB) #04-01-38-008 to address problems with the heating system, blower control, and airflow on the following models:

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

If you find that you cannot control any of the heater controls, heating, air conditioning, or airflow, or the air only blows through the defroster vents, follow the advice in this TSB. If you use a scan tool, you may also find the following trouble codes have been set:
B0229 Recirculation Actuator, B0414 Left Air Temperature Actuator, B0424 Right Air Temperature Actuator, B3770 Mode Actuator

The cause of all these problems may be a wiring harness that’s been damaged. The HVAC actuator harness may have come in contact with a metal support brace under the instrument panel and the brace may have cut through the wiring actuator control or feedback wires. Open the instrument panel door and fold it down. Then locate the actuator harness on the left side of the opening. Repair any damage to the actuator harness wiring and install protective plastic conduit over the harness. Install friction tape over the sharp edge of the instrument panel brace. Then clear the trouble codes and test the repair.

© 2012 Rick Muscoplat

Posted on by Rick Muscoplat


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