ASI Resolution - Blower Motor Noise on Second Speed Setting (Replace HVAC Control Module)

This bulletin is being revised to provide the correction and warranty information, which is now available for Advanced Service Information Bulletin Number 04-01-38-004. Please discard Corporate Bulletin Number 04-01-38-004 (Section 01 -- HVAC).

Some customers may comment on a blower motor noise on the second speed setting.

This condition may be caused by the Heating, Ventilation and Air Conditioning (HVAC) control module using Pulse Width Modulation (PWM) to control the blower motor speed. PWM control of the blower motor only occurs on the second speed setting. For speeds 1, 3 and 4 the blower motor is controlled through the use of blower motor resistors. For high speed, setting 5, the HVAC control module provides a direct path to ground, without the use of resistors, to control the blower motor speed.

Technicians are to install a new HVAC Control Module, P/N 15230831, which uses a new PWM control method. Refer to the HVAC Control Module Replacement procedure in SI for replacement instructions (Document ID #1343409).

Please contact all customers that were told they would be called when a repair became available.

Parts are currently available from GMSPO.

For vehicles repaired under warranty, use: