heater and airconditioner on at same time

Bulletin No.: 06-01-38-003

Date: April 27, 2006

TECHNICAL

Subject:
Intermittent Ticking Noise from I/P, Poor A/C Performance, HVAC DTCs B0229, B0414, B0424, B3770 (Reprogram HVAC Control Module)

Models:
2004-2006 Cadillac Escalade Models
2004-2006 Chevrolet Avalanche, Silverado, Suburban, Tahoe
2004-2006 GMC Sierra Models, Yukon Models

with Air Conditioning (RPOs CJ2, CJ3)

Condition

Some customers may comment on one or more of the following concerns:

^ Intermittent ticking/clicking noise from the instrument panel.

^ Recirculation mode does not work or Air Conditioning (A/C) system performance is poor during high ambient temperatures.

^ Unable to control the driver side temperature.

^ Unable to control the passenger side temperature.

^ Unable to change the front system modes.

Cause

This condition may be caused by the Heating, Ventilation and Air Conditioning (HVAC) actuators that may hunt for the correct commanded position. This cycling may cause a clicking or ticking noise.

An overtravel of the HVAC system control doors may cause one or more of the concerns listed above. If an overtravel occurs, a Diagnostic Trouble Code (DTC) will be set, and the door will go to a preset default position. When a system door defaults, that door will stay at the default position until the DTC is cleared. After the DTC is cleared, the door will operate properly until the overtravel condition re-occurs.