Subject:HVAC System Cannot Be Controlled Or Defaults To Defrost Mode (Repair HVAC Actuator Harness) #04-01-38-008 - (06/17/2004)
Models:2003-2005 Cadillac Escalade, Escalade ESV, Escalade EXT
2003-2005 Chevrolet Avalanche, Silverado, Suburban, Tahoe
2003-2005 GMC Sierra, Yukon, Yukon XL
• 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.Cause
• 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
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.
Locate the HVAC actuator harness contact point shown by the arrow in the above illustration. The illustration is of the instrument panel with the instrument panel compartment door opened and folded downward. The actuator harness is located in the left side of the opening in the instrument panel.
Technicians are to inspect the HVAC actuator harness for contact with the instrument panel support brace. 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. Clear the diagnostic trouble codes and verify proper HVAC system operation.
For vehicles repaired under warranty, use:
Wiring And/Or Connector - HVAC System - Repair Or Replace
Use applicable labor operation time.