Sierra 1500 2WD V8-5.3L Hybrid (2004)
Wiring Harness HVAC: All Technical Service Bulletins
A/C - Defaults To Defrost Mode/Poor Control
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
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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.
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Technicians may find that the following diagnostic trouble codes have set:
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B0229 Recirculation Actuator
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B0414 Left Air Temperature Actuator
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B0424 Right Air Temperature Actuator
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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.
Correction
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.
