Blower Relay - Buzzing When Ignition Is Turned OFF: Overview

NUMBER: 24-26-99

GROUP: Heating & A/C

DATE: Nov. 19, 1999

SUBJECT:
Buzzing Noise Heard When Ignition Key Is Switched To "Off"

OVERVIEW:
This bulletin involves bypassing the blower motor fan voltage reduction relay.

NOTE:
THE FUNCTION OF THE BLOWER MOTOR FAN VOLTAGE REDUCTION RELAY IS TO REDUCE THE BLOWER MOTOR FAN SPEED SLIGHTLY WHILE IN THE HEAT MODE WHICH DECREASES THE AMOUNT OF FAN NOISE WHILE IN THE HEAT MODE. CUSTOMERS SHOULD BE MADE AWARE THAT WHEN THIS BULLETIN'S PROCEDURE HAS BEEN COMPLETED, THE BLOWER WILL OPERATE AT A SLIGHTLY HIGHER SPEED IN THE HEAT MODE CAUSING A SLIGHTLY HIGHER FAN NOISE LEVEL.

MODELS:
2000 (DN) Durango

NOTE:
THIS BULLETIN APPLIES TO VEHICLES EQUIPPED WITH REAR A/C.

SYMPTOM/CONDITION:
A high pitched buzzing noise may be heard when the ignition switch is turned to the OFF position. The noise will only be heard if the rear A/C is in the ON position and the front A/C is in the OFF position prior to turning the ignition switch to OFF. The noise is the result of the rear A/C blower fan creating a voltage source as the fan is coming to a stop and back-feeding the voltage reduction relay. The length of time the relay buzzes is based upon what speed the fan is at when the ignition is turned OFF.

DIAGNOSIS:

Turn the ignition key to the RUN position. Turn the front mode control to the heat position and the rear A/C blower fan to the high speed position. Then, turn the ignition key to the OFF position. If a high pitched buzz is heard when the ignition key is switched OFF, perform the repair procedure.

PARTS REQUIRED:

AR(1) 04778570 Heat Shrink Tubing

EQUIPMENT REQUIRED:

Soldering Gun
Rosin Core Solder
Electrical Tape
Terminal Removal Tool - 6680-4S

POLICY: Reimbursable within the provisions of the warranty.

TIME ALLOWANCE:

Labor Operation No: 08-90-90-95 0.3 Hrs.

FAILURE CODE: XX - Service Adjustment