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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 tests for auxiliary blower motor operation in any speed setting.
  2. 5:  This step identifies if the auxiliary HVAC control module is commanding the auxiliary blower motor to operate at HI speed.
  3. 8:  This step verifies that power is being supplied to the auxiliary blower motor.
  4. 9:  This step tests for a possible open in the auxiliary blower motor ground circuit or a poor motor.
Blower Motor Inoperative - Auxiliary (W/O Sunroof)

Step Action Value(s) Yes No
Schematic Reference:  HVAC Schematics  
DEFINITION: The auxiliary blower motor is inoperative in 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 front auxiliary HVAC control module blower switch in each speed position.
  3. Place the front auxiliary HVAC control module blower switch in the rear position.
  4. Place the rear auxiliary HVAC control module blower switch in each speed position.
Are both auxiliary control modules inop in all speeds?		 - Go to Step 5  Go to Step 3 
3 Does only the front auxiliary control module operate? - Go to Step 11  Go to Step 4 
4 Does only the rear auxiliary control module operate? - Go to Step 15  Go to TESTING FOR INTERMITTENT AND POOR CONNECTIONS
5 
IMPORTANT: Place the front auxiliary HVAC control switch in the REAR position. Place the rear auxiliary HVAC control switch in the HI speed position. Place the MODE selector in any position except AUTO. This will ensure a full speed condition when the auxiliary blower motor is commanded to an ON position. Failure to do this may result in a misdiagnosis.
  1. Place the rear auxiliary HVAC control module blower switch in the max. speed position.
  2. Place the MODE selector in the FLOOR position.
  3. Command the auxiliary blower motor to the ON state.
  4. Observe the auxiliary blower motor PWM parameter.
Is the auxiliary blower motor PWM parameter at the specified value?		 98% Go to Step 6  Go to Step 17 
6
  1. Disconnect the auxiliary blower motor connector.
  2. Connect a test lamp between the auxiliary blower motor supply circuit and a known good ground.
  3. Rotate the fan control switch from the min. to max. speed position.
Does the test lamp illuminate and change intensity?		 - Go to Step 7  Go to Step 9 
7
  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 LOW to HI speed position.
Does the test lamp illuminate and change intensity?		 - Go to Step 19  Go to Step 8 
8  Test the rear blower motor control module ground circuit for an open. Refer to CIRCUIT TESTING and WIRING REPAIRS .
Did you find and correct the condition?		 - Go to Step 20  Go to Step 14 
9  Test the rear blower motor control module battery positive voltage circuit for an open or short to ground. Refer to CIRCUIT TESTING and WIRING REPAIRS .
Did you find and correct the condition?		 - Go to Step 20  Go to Step 10 
10 Test the rear Heater and A/C blower motor control module control circuit for a high resistance, open or short to voltage. Refer to CIRCUIT TESTING and WIRING REPAIRS .
Did you find and correct the condition?		 - Go to Step 20  Go to Step 12 
11 Test the blower speed control circuit between the front and rear auxiliary HVAC control modules.
Did you find and correct the condition?		 - Go to Step 20  -
12
  1. With a volt meter backprobe the auxiliary blower motor control circuit at the auxiliary blower motor control module.
  2. Rotate the fan control switch from the LOW to HI speed position.
Does the voltage vary between the specified value?		 0.4-4.0 V Go to Step 16  Go to Step 13 
13 Inspect for poor connections at the harness connector of the rear HVAC control module. Refer to TESTING FOR INTERMITTENT AND POOR CONNECTIONS and .
Did you find and correct the condition?		 - Go to Step 20  Go to Step 15 
14 Inspect for poor connections at the harness connector of the auxiliary 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 20  Go to Step 18 
15 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 20  Go to Step 16 
16 Replace the front HVAC control module. Refer to HVAC Control Assembly Replacement - Front Auxiliary .
Did you complete the replacement?		 - Go to Step 20  -
17 Replace the rear HVAC control module. Refer to HVAC Control Assembly Replacement - Front Auxiliary .
Did you complete the replacement?		 - Go to Step 20  -
18 Replace the auxiliary blower motor control module. Refer to Blower Motor Processor Replacement - Auxiliary .
Did you complete the replacement?		 - Go to Step 20  -
19 Replace auxiliary blower motor. Refer to BLOWER MOTOR - AUXILIARY .
Did you complete the replacement?		 - Go to Step 20  -
20 Operate the system in order to verify the repair.
Did you correct the condition?		 - System OK Go to Step 2 
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