Test Description

WARNING: This page is about a different car, the 2002 Oldsmobile Bravada, 2002 GMC Envoy XL, 2002 GMC Envoy, and 2002 Chevrolet TrailBlazer. However, it is still accessible from the selected car via links, so may be relevant.

2: This step verifies that the HVAC control module Fan Up Switch parameter matches the requested state of the blower motor switch.
3: This step verifies that the HVAC control module Fan Down Switch parameter matches the requested state of the blower motor switch.

Blower Motor Malfunction

Step	Action	Values	Yes	No
Schematic Reference: HVAC Schematics Connector End View Reference: HVAC Connector End Views DEFINITION: The blower motor operates in at least one speed position.
1	Did you perform the HVAC Diagnostic System Check?	-	Go to Step 2	Go to Diagnostic System Check - HVAC Systems - Automatic
2	Turn ON the ignition, with the engine OFF. With a scan tool, observe the Fan Up Button parameter in the Heating and Air Conditioning data list. Activate the fan up switch. Does the scan tool indicate that the Fan Up Button parameter changes state?	-	Go to Step 3	Go to Step 10
3	With a scan tool, observe the Fan Down Button parameter in the Heating and Air Conditioning data list. Activate the fan down switch. Does the scan tool indicate that the Fan Down Button parameter changes state?	-	Go to Step 4	Go to Step 10
4	Place the blower motor switch in each speed position. Does the blower motor operate at the desired speeds?	-	Go to TESTING FOR INTERMITTENT CONDITIONS AND POOR CONNECTIONS in Wiring Systems	Go to Step 5
5	Disconnect the harness connector of the blower motor control processor. Measure the voltage between the battery positive voltage circuit and the ground circuit of the blower motor control processor. Does the voltage measure within the specified range?	10-14 V	Go to Step 6	Go to Step 8
6	Connect the blower motor control processor. Disconnect the harness connector of the HVAC control module. Measure the voltage on the blower motor speed control circuit. Does the voltage measure within the specified range?	4.5-5.5 V	Go to Step 9	Go to Step 7
7	Test the control circuit of the blower motor control processor for a high resistance. Refer to CIRCUIT TESTING and WIRING REPAIRS in Wiring Systems. Did you find and correct the condition?	-	Go to Step 14	Go to Step 9
8	Test the battery positive voltage circuit of the blower motor control processor for a high resistance. Refer to CIRCUIT TESTING and WIRING REPAIRS in Wiring Systems. Did you find and correct the condition?	-	Go to Step 14	Go to Step 11
9	Inspect for poor connections at the harness connector of the blower motor control processor. Refer to TESTING FOR INTERMITTENT CONDITIONS AND POOR CONNECTIONS and CONNECTOR REPAIRS in Wiring Systems. Did you find and correct the condition?	-	Go to Step 14	Go to Step 12
10	Inspect for poor connections at the harness connector of the HVAC control module. Refer to TESTING FOR INTERMITTENT CONDITIONS AND POOR CONNECTIONS and CONNECTOR REPAIRS in Wiring Systems. Did you find and correct the condition?	-	Go to Step 14	Go to Step 13
11	Repair a high resistance in the ground circuit of the blower motor control processor. Refer to CIRCUIT TESTING in Wiring Systems. Did you complete the repair?	-	Go to Step 14	-
12	Replace the blower motor control processor. Refer to Blower Motor Control Processor Replacement . Did you complete the replacement?	-	Go to Step 14	-
13	IMPORTANT: Perform the recalibration procedure for the HVAC control module. Replace the HVAC control module. Refer to HVAC Control Module Replacement .Did you complete the replacement?	-	Go to Step 14	-
14	Operate the system in order to verify the repair. Did you correct the condition?	-	System OK	Go to Step 2