A/C - Noise From HVAC in Cold/Cool Weather
TECHNICALBulletin No.: 09-01-39-003A
Date: June 04, 2009
Subject: Whistle, Tone or High Pitched Hum Noise From HVAC in Cold/Cool Weather (Replace Blower Motor Control Processor)
Models:
2007-2009 Chevrolet Malibu
2007-2009 Pontiac G6
2007-2009 Saturn AURA
All Equipped with Automatic HVAC (RPO C68)
Supercede:
This bulletin is being revised to add the Saturn AURA. Please discard Corporate Bulletin Number 09-01-39-003 (Section 01 - HVAC).
Condition
Some customers may comment on a tone, whistle or high pitched hum type noise when operating their vehicle in cold or cool weather with the Automatic HVAC "On". The noise may be present while the vehicle is first warming up or after the interior has reached the requested temperature and the blower speed is ramping down.
This condition can be verified by turning off the HVAC which will eliminate the whistle, if the HVAC is the source.
Cause
This condition may be caused by a resistor internal to the blower motor control processor that may be emitting the objectionable noise.
Correction
Replace the blower motor control processor following this procedure
1. Remove the right side I/P closeout panel. Refer to Instrument Panel Insulator Panel Replacement - Right Side.
2. Disconnect the blower motor control processor wire harness connector.
3. Remove the blower motor control processor screws.
4. Remove the blower motor control processor.
5. Install the new blower motor control processor, GM P/N 20773421.
6. Tighten the blower motor control processor screws.
Tighten
Tighten the screws to 1.5 Nm (13 lb in).
7. Connect the blower motor control processor wire harness connector.
8. Install the right side I/P closeout panel. Refer to Instrument Panel Insulator Panel Replacement - Right Side.
Parts Information
Warranty Information
For vehicles repaired under warranty, use the table above.
Disclaimer