For 1990-2009 cars

Step | Action | Values | Yes | No
--- | --- | --- | --- | ---
Schematic Reference: HVAC Schematics Connector End View Reference: HVAC Connector End Views DEFINITION: The blower motor is inoperative in all speed positions.
1 | Did you perform the HVAC Diagnostic System Check? | -- | Go to Step 2 | Go to Diagnostic System Check - HVAC Systems - Automatic
2 |

1. Turn ON the ignition, with the engine OFF.
2. Place the blower switch in each speed position.

Does the blower motor operate in any speed position?

--

Go to Blower Motor Malfunction

Go to Step 3

3 |

1. Turn OFF the ignition.
2. Disconnect the blower motor connector.
3. Turn ON the ignition, with the engine OFF.
4. Connect a test lamp between the blower motor supply voltage circuit and the blower motor ground circuit.
5. Place the blower switch in the maximum speed position.

Does the test lamp illuminate?

--

Go to Step 10

Go to Step 4

4 | Test the battery positive voltage circuit of the blower motor for an open, high resistance or short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 16 | Go to Step 5
5 | Test the ground circuit of the blower motor control processor for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 16 | Go to Step 6
6 | Important: The blower motor control processor connector and the HVAC control module connectors must be connected to correctly perform the test.

1. Backprobe and measure the voltage from the blower speed request signal circuit at the HVAC control module to a good ground.
2. With a scan tool, command the blower motor from Low to High.

Does the voltage measure near the specified values for each commanded state?

3.0 V Low

9.0 V High

Go to Step 7

Go to Step 9

7 | Test the blower motor speed control circuit between the blower motor and the blower motor control processor for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? |  | Go to Step 16 | Go to Step 8
8 | Test the blower speed control circuit between the blower motor and the blower motor control processor for an open, short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? |  | Go to Step 16 | Go to Step 11
9 | Test the blower speed request signal circuit of the HVAC control module for an open, short to ground or short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. 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 blower motor. 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 16 | Go to Step 13
11 | 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 16 | Go to Step 14
12 | 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 16 | Go to Step 15
13 | Replace the blower motor. Refer to Blower Motor Replacement in Heating, Ventilation and Air Conditioning. Did you complete the replacement? | -- | Go to Step 16 | --
14 | Replace the blower motor control processor. Refer to Blower Motor Control Processor Replacement . Did you complete the replacement? | -- | Go to Step 16 | --
15 | Important: Perform the recalibration procedure for the HVAC control module. Replace the HVAC control module. Refer to HVAC Control Module Replacement in Body Control System. 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