A/C - Odor at Start up in Humid Climates
File In Section: 1 - HVACBulletin No.: 53-12-12A
Date: December, 1996
Subject:
Air Conditioning Odor at Start Up in Humid Climates
(Disinfect Evaporator Core, Install Delayed Blower Control Package)
Models:
1993-96 Passenger Cars (Except GEO)
1993-96 Light Duty Models (Except Tracker)
This bulletin is being revised to update the wiring diagrams, add the Corvette (with RPO C60) and delete medium/heavy duty trucks. Please discard Corporate Bulletin Number 53-12-12 (Section 1 - HVAC).
Condition
Some owners may comment on odors emitted from the air conditioning system, primarily at start up in hot, humid climates.
Cause
This odor may be the result of microbial growth on the evaporator core. When the blower motor fan is turned on, the microbial growth may release an unpleasant musty odor into the passenger compartment.
Correction
To remove odors of this type, it is necessary to eliminate the microbial growth and prevent its recurrence. To accomplish this, these two procedures must be completed.
^ Deodorize the evaporator core using Deodorizing Aerosol Kit, P/N 12377951 (AC Delco 15-102).
^ Install the new A/C Delayed Blower Control Package, P/N 12370470, (AC Delco 15-8632).
The blower control package will enable the blower to run at high speed for five (5) minutes. It will do so approximately fifty (50) minutes after the ignition has been turned off if the compressor had been engaged for four (4) or more minutes prior to shutting off engine. By doing so, the evaporator case and core are dried out, reducing the chances of a recurring A/C odor.
Procedure
1. Visually inspect the air conditioning evaporator drain hose for obstructions or working condition.
2. Apply deodorizing aerosol as described in the instructions supplied with the kit. Once the deodorizer has been applied, some of the mixture may overflow from the drain hose.
3. The chart identifies specific instructions for each vehicle. This chart will identify the proper deodorizing procedure, template and wiring diagram. Deodorizing the evaporator case can easily be done by removing the blower motor resistor and tape off opening. The nozzle can now be inserted through a pierced hole in the tape to deodorize the evaporator case. For some of the vehicles specified below, a drilling procedure is identified in the deodorizing instructions. This type of alternative procedure and others can be done by using the referenced templates in the chart.
4. Complete detailed installation instructions are supplied with the blower control package.
Important:
A. 1996 ONLY (Use blower resistor location for drilling procedure)
B. 1994-1996 ONLY
Refer to appropriate Service Manual for enabling afterblow feature through on-board diagnostics.
Parts Information
Parts are currently available from GMSPO.
Warranty Information
For vehicles repaired under warranty, use as shown.
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