Rainier AWD L6-4.2L VIN S (2005)
Control Module HVAC: Customer Interest
A/C - Musty Odors On Start Up
Bulletin No.: 05-01-39-002A
Date: March 17, 2006
TECHNICAL
Subject:
Musty Odor from HVAC System (Reprogram HVAC Control Module to Enable Afterblow Function)
Models:
2004-2006 Buick Rainier
2003-2006 Chevrolet TrailBlazer, TrailBlazer EXT
2003-2006 GMC Envoy, Envoy XL
2004-2005 GMC Envoy XUV
2003-2004 Oldsmobile Bravada
with Automatic Temperature Control HVAC System (RPO CJ2)
Supercede:
This bulletin is being revised to add the 2006 model year and update the calibration release date. Please discard Corporate Bulletin Number
05-01-39-002 (Section 01 - HVAC).
Condition
Some customers may comment on a musty odor from the Heating, Ventilation and Air Conditioning (HVAC) system. This condition occurs most often
on initial start up after the vehicle was driven on a hot humid day.
Cause
This condition may be caused by condensate build-up on the evaporator core, which does not evaporate by itself in high humidity conditions.
Correction
Important:
The afterblow function should not be enabled until after the purpose and operation of it is explained to your customer and they approve of the
change. Once the afterblow function is enabled there are no calibrations currently released to disable it.
Technicians are to reprogram the HVAC Control Module with an updated software calibration that will enable the afterblow function. The new
calibration will be released beginning with TIS satellite data update version 2.0, which was made available February 5, 2006. The blower motor will turn
on approximately 10 minutes after the vehicle is shut off. The blower motor will run continuously for 10 minutes at a 30% duty cycle. The afterblow
function will only activate if the air conditioning compressor was engaged during conditions of high ambient temperature. If the vehicle is started within
10 minutes of the last key off, the afterblow function from the previous key cycle will be cancelled.
Technicians should not attempt to reprogram a vehicle with a Manual Temperature Control HVAC system (RPO CJ3).
Technicians should perform this HVAC Control Module reprogram instead of installing the Electronic Evaporator Dryer Module Kit referred to in the
Air Conditioning Odor bulletin, Corporate Bulletin Number 99-01-39-004A.
Warranty Information
