For 1990-2009 cars

# ELECTRONIC CLIMATE CONTROL BLOWER SPEED TOO HIGH

#### 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 E 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 Imm-2mm gap between the panel and the script. This allows more air flow over the in-car sensor and eiiminates 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.

If script stands out away from the instrument panel (lmm-2mm), 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 --------------------- ------- --- --- --- --- --- Script Replace T6553 .7 PROM Replace N4801 .5

General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.