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Test Description

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The number(s) below refer to the step number(s) on the diagnostic table.

  1. 2:  This step will determine if one or more blower speeds are inoperative.
  2. 3:  This step verifies if the rear HVAC control switch is attempting to control the auxiliary blower motor speed.
  3. 4:  This step verifies if the front HVAC control switch is attempting to control the auxiliary blower motor speed.
Blower Motor Malfunction - Auxiliary (W/O Sunroof)

Step Action Value(s) Yes No
Schematic Reference:  HVAC Schematics  
DEFINITION: The auxiliary blower motor operates in at least one, but not all, speed positions.
1 Did you review the auxiliary HVAC operation and perform the necessary inspections? - Go to Step 2  Go to Symptoms - HVAC Systems - Automatic 
2 
IMPORTANT: The rear auxiliary HVAC control switch will only function if the front auxiliary HVAC control switch is placed in the REAR position.
  1. Turn ON the ignition, with the engine OFF.
  2. Place the auxiliary HVAC control module blower switch in each speed position.
Does the auxiliary blower motor operate in each speed position?		 - Go to TESTING FOR INTERMITTENT AND POOR CONNECTIONS Go to Step 3 
3 
IMPORTANT: Place the front auxiliary HVAC control module blower switch in the REAR position. Place the MODE selector in any position except AUTO. Failure to do this may result in a misdiagnosis.
  1. Place the MODE selector in the FLOOR position.
  2. Observe the auxiliary blower motor PWM parameter.
  3. Rotate the rear HVAC control module blower switch from the min. to max. speed positions.
Does the auxiliary blower motor PWM parameter increase within the specified range?		 0-98% Go to Step 4  Go to Step 5 
4 
  1. Place the front auxiliary HVAC control module blower switch in the min. speed position.
  2. Place the MODE selector in the FLOOR position.
  3. Observe the auxiliary blower motor PWM parameter.
  4. Rotate the front auxiliary HVAC control module blower switch from the min. to max. speed positions.
Does the auxiliary blower motor PWM parameter increase within the specified range?		 0-98% Go to Step 7  Go to Step 6 
5 Test the 5 volt reference and low reference circuits between the front and rear HVAC control modules for an open, a short to voltage, short to ground or a high resistance. Refer to CIRCUIT TESTING and WIRING REPAIRS .
Did you find and correct the condition?		 - Go to Step 9  Go to Step 10 
6 Test the blower speed control circuit between the front and rear HVAC control switches for an open or a high resistance. Refer to CIRCUIT TESTING and WIRING REPAIRS .
Did you find and correct the condition?		 - Go to Step 16  Go to Step 8 
7 Test the rear blower motor control module control circuit for a short to voltage, high resistance. Refer to CIRCUIT TESTING and WIRING REPAIRS .
Did you find and correct the condition?		 - Go to Step 16  Go to Step 11 
8
  1. Disconnect the auxiliary blower motor connector.
  2. Connect a test lamp between the auxiliary blower motor supply circuit and ground circuit.
  3. Rotate the fan control switch from the min. to max. speed position.
Does the test lamp illuminate and change intensity?		 - Go to Step 15  Go to Step 11 
9 Inspect for poor connections at the harness connector of the rear HVAC control module. Refer to TESTING FOR INTERMITTENT AND POOR CONNECTIONS and CONNECTOR REPAIRS .
Did you find and correct the condition?		 - Go to Step 16  Go to Step 12 
10 Inspect for poor connections at the harness connector of the front HVAC control module. Refer to TESTING FOR INTERMITTENT AND POOR CONNECTIONS and CONNECTOR REPAIRS .
Did you find and correct the condition?		 - Go to Step 16  Go to Step 13 
11 Inspect for poor connections at the harness connector of the rear blower motor control module. Refer to TESTING FOR INTERMITTENT AND POOR CONNECTIONS and CONNECTOR REPAIRS .
Did you find and correct the condition?		 - Go to Step 16  Go to Step 14 
12 Replace the rear HVAC control module. Refer to HVAC Control Assembly Replacement - Front Auxiliary .
Did you complete the replacement?		 - Go to Step 16  -
13 Replace the front HVAC control module. Refer to HVAC Control Assembly Replacement - Front Auxiliary .
Did you complete the replacement?		 - Go to Step 16  -
14 Replace the rear blower motor control module. Refer to Blower Motor Processor Replacement - Auxiliary .
Did you complete the replacement?		 - Go to Step 16  -
15 Replace the auxiliary blower motor. Refer to BLOWER MOTOR - AUXILIARY .
did you complete the replacement?		 - Go to Step 16  -
16 Operate the system in order to verify the repair.
Did you correct the condition?		 - System OK Go to Step 2 
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