A/C - Unbalanced Defroster Performance
Group Ref.: HVACBulletin No.: 331223A
Date: December, 1993
SUBJECT:
UNBALANCED DEFROSTER PERFORMANCE
(REPLACE DEFROSTER MODULAR DUCT ASSEMBLY)
MODELS:
1991-93 BUICK PARK AVENUE
1991-93 CADILLAC DEVILLE
1991-93 OLDSMOBILE NINETY EIGHT
1992-93 BUICK LESABRE
1992-93 OLDSMOBILE EIGHTY EIGHT
1992-93 PONTIAC BONNEVILLE
THIS BULLETIN IS BEING REVISED TO SPECIFY REFERENCES TO FIGURES 3 AND 4. THESE FIGURES WERE INCLUDED IN THE ARTWORK, BUT WERE NOT REFERENCED IN THE BULLETIN TEXT.
CONDITION:
Some vehicles may exhibit unbalanced air flow from the windshield defroster outlets. This usually results in the passenger side of the windshield defrosting faster than the driver's side.
CAUSE:
Unbalanced flow of heated air through defroster outlets.
CORRECTION:
Replace defroster modular duct assembly with a revised design that provides balanced outlet air flow.
Cadillac, Pontiac, Oldsmobile -
CAUTION:
If vehicle is equipped with Supplemental Inflatable Restraint (SIR), refer to CAUTIONS in Section 9J under ON VEHICLE SERVICE and the SIR component and wiring location view in Section 9J before performing service on or around SIR components or wiring. Failure to follow CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded SIR system repairs.
Buick -
CAUTION:
If vehicle is equipped with Supplemental Inflatable Restraint (SIR), refer to the Supplemental Inflatable Restraint (SIR) section of the ESM for CAUTIONS under ON VEHICLE SERVICE. Also refer to SIR component and wiring location views before performing service on or around SIR components or wiring. Failure to follow CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded SIR system repairs.
REMOVE:
1. I/P carrier. Refer to Service Manual, Section 8C (Cadillac, Oldsmobile and Pontiac); ESM General Air Conditioning Section (Buick).
Notice:
Be sure to loosen lower steering column mounting bracket before lowering steering column or bracket damage will result.
2. Vacuum harness retainers and vacuum lines from actuators. Note positions.
3. Defroster modular duct assembly. (Figure 1)
4. Trim off stud, at left of center over lighting control module, flush with nut. (Figure 1)
Notice:
Be sure to cover carpet and seats to shield from sparks, if cutting wheel or grinder is used.
5. Buick, Oldsmobile, Cadillac: Remove and modify cross car duct as follows to accommodate extended defrost A/C door crank arm.
Pontiac:
Cross car duct and replace with revised duct that accommodates extended A/C door crank arm swing.
Cadillac (Figure 2), Buick (Figure 3), Oldsmobile (Figure 4) -
A. Evenly heat the right side of the crank arm well until plastic becomes pliable (plastic starts to get shiny).
Notice:
Extreme care must be taken to avoid melting through the plastic.
B. Use a large socket to depress well edge. Plastic must be displaced approximately 10 mm.
If cross car duct should melt through, a similar piece of plastic should be used to repair area. Pop rivet new piece to cross car duct using "Shoe Goop"* as an adhesive/sealant. Shoe Goop is the only sealant that will adequately stick to this type of plastic.
*We believe this source and their equipment to be reliable. There may be additional manufacturers of such equipment. General Motors does not endorse, indicate any preference for or assume any responsibility for the products or equipment from this firm or for any such items which may be available from other sources.
Pontiac:
Only vehicles prior to VIN breakpoint 220200 require cross car duct replacement.
INSTALL:
1. New defroster modular duct assembly. (Figure 1)
2. Buick, Oldsmobile, Cadillac: Hold cross car duct tight to modular duct interface. Check defrost A/C valve crank arm travel to ensure no interference with duct.
3. Vacuum harness retainers and vacuum lines to actuators.
4. Foam seals to air distribution chamber at cross car duct interface.
5. I/P carrier. Refer to Service Manual, Section 8C (Cadillac, Oldsmobile and Pontiac); ESM General Air Condition Section (Buick).
To test repair, adjust to full blower in heat or defrost mode; no air should pass through A/C ducts. If air passes through ducts, clearance is insufficient and cross car duct requires further modification.
PARTS INFORMATION
52455869 - Seal
12536299 - Seal
52463697 - Modular Duct Assembly
25614927 - Cross Car Duct (Pontiac Only)
Parts are currently available from GMSPO.
WARRANTY INFORMATION
Labor Operation Number: T3377
Labor Time:
Cadillac - 2.3
Buick - 2.4
Oldsmobile "C" - 2.3 (add .7 W/console)
Oldsmobile "H" - 2.3
Pontiac - 2.0 (add .1 to replace cross car duct prior to VIN # 220200) (add .7 w/console)