A/C - Condensation Drips From Heater Duct
91cadillac04
Bulletin No.: T-91-89
File in Group: 1
Number: 78
Corp. Ref. No.: 101101
Date: May, 1991
SUBJECT:
CONDENSATION DRIPPING FROM HEATER DUCT
MODELS AFFECTED:
1991 DE VILLES AND FLEETWOODS
Some 1991 DeVilles and Fleetwoods in high ambient, high humidity areas may experience a condition where condensation drips from the heater/floor duct when the blower is on high speed and the vehicle is undergoing quick acceleration or sharp turns.
This condition may be caused by high speed air picking up water in the air mix door area that normally drains out of the HVAC case, blowing it past the joint between the air distribution duct and the HVAC case where it then leaks out onto the floor.
If inspection of drain hose shows no blockage, repair this condition by installing a watertight dam on the floor of the HVAC case overlapping the air distribution duct joint. Part number 52460676 is currently available from GMSPO.
CAUTION: This vehicle is equipped with the Supplemental Inflatable Restraint (SIR) system. Refer to cautions in Section 9J under on-vehicle service before performing service on or around SIR components or wiring. Failure to follow cautions could result in possible air bag deployment, personal injury, or unneeded SIR system repairs.
CAUTION: Before removing or installing any electrical components disconnect the negative battery cable to help prevent personal injury and/or damage to the vehicle or its components.
Figure 1 - Air Distribution Duct Assembly:
1. Follow Section 1C of the 1991 DeVille/Fleetwood Service Information Manual to remove the air distribution duct assembly from the dash. Refer to Figure 1.
2. Scuff the mounting surface of the dam and the HVAC case with 220 grit sandpaper. This is the outside lip of the module case that fits inside the modular duct. Be sure both surfaces are clean and dry when finished.
3. Wipe the case and the dam clean with 3M No. 08984 general purpose cleaner or equivalent to remove any traces of contamination that may prevent a good bond between the pieces.
4. Apply adhesive, 3M No.08641 or equivalent, to the mounting surfaces of the dam and the HVAC case. Place the dam in the illustrated position. Make sure that the mounting tab is facing the heater core.
5. Temporarily tape the dam in position for 30 minutes to allow the sealer to set.
In order for this repair to be effective it is important that the dam be completely watertight. If necessary, run a second bead of sealer around the adjoining surfaces.
6. Add push-on retainer nut, P/N 11501937, to maintain actuator A/C defroster door line position.
7. Remove tape and reassemble the HVAC and dash assembly per Section 1C of the 1991 DeVille/Fleetwood Service Information Manual.
For warranty purposes use Labor Operation T5220 at 1.8 hours (includes SIR disable and idle learn time).