ECC System - Blower Speed Too High

91cadillac06

Bulletin No.: T-91-100
File in Group: 1
Number: 79
Corp. Ref. No.: 101104
Date: July, 1991


SUBJECT:
ECC BLOWER SPEED TOO HIGH (NEW PART)

MODELS AFFECTED:
1991 DE VILLES AND FLEETWOODS


Some 1991 DeVilles and Fleetwoods (start of production through M4305189) may experience excess air from the side window defog or defrost creating a drafty climate from the ECC or an air "rush" noise from the HVAC outlets caused by the blower speed remaining on high speed for an extended period while set in "auto" mode.

Prior to the VIN breakpoint M4305189, a high blower speed was used to pull more air over the in-car sensor to prevent temperature control "drift" or "overshoot". However, a change was made earlier in the 1991 model year moving the "Cadillac" script above the glove box. This change moves the script from a recessed position in the instrument panel to a "stand out" position leaving a 1 mm - 2 mm gap between the panel and the script. This allows more air flow over the in-car sensor and eliminates the need for the increased blower speed.

To repair this condition it is necessary to ensure that the revised script is coordinated with the new PROM to reduce blower speed by carefully following the procedure listed below:

1. Inspect "Cadillac" script located on the instrument panel above the glove box door.

a. If script is recessed or flush with the instrument panel, remove and replace with P/N 25602888 and install new PROM, P/N 16164048.

b. If script stands out away from the instrument panel (1 mm - 2 mm), check PROM I.D. (diagnostic parameter P.3.3). If it is not I.D. 58, install new PROM, P/N 16164048.

Parts are currently available from GMSPO.


WARRANTY INFORMATION VEHICLE SERIES
Operation
Operation Description Number C D E J K V

Script Replace T6553 .7
PROM Replace N4801 .5