For 1990-2009 cars

Step | Action | Yes | No
--- | --- | --- | ---
Schematic Reference: HVAC Schematics Connector End View Reference: HVAC Connector End Views Definition: The blow motor does not work in any speed position.
1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Blower Motor Malfunction | Go to Diagnostic System Check - Vehicle
2 |

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

Does blower motor work in any speed position?

Go to Blower Motor Malfunction

Go to Step 3

3 |

1. Turn OFF the ignition.
2. Disconnect the blower motor connectors.
3. Turn ON the ignition, with the engine OFF.
4. Turn ON the HVAC Control Module.
5. Connect a test lamp between the blower motor supply voltage circuit and blower motor fan control circuit.
6. Place the blower motor switch in the maximum speed position.

Does the test light illuminate?

Go to Step 14

Go to Step 4

4 | Probe the supply voltage circuit of the blower motor with a test lamp that is connected to ground well. Does the test light illuminate? | Go to Step 9 | Go to Step 5
5 |

1. Turn OFF the ignition.
2. Remove the blower motor relay.
3. With a test lamp connected to ground, probe the battery positive voltage circuit at the switch side and coil side of the relay connector.

Does the test light illuminate?

Go to Step 6

Go to Step 17

6 |

1. Turn ON the ignition, with the engine OFF.
2. Turn ON the HVAC Control Module.
3. Probe control circuit of blower motor relay with a test lamp which is connected to the voltage.

Does the test light illuminate?

Go to Step 7

Go to Step 8

7 | Test blower motor supply voltage circuit for open, short to ground or for a high resistance. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 22 | Go to Step 13
8 | Test blower motor relay control circuit for open, short to voltage or for a high resistance. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 22 | Go to Step 16
9 |

1. Turn OFF the ignition.
2. Disconnect the blower control processor.
3. Turn ON the ignition.
4. Turn the blower switch to high speed position.
5. Probe the speed control circuit of the blower motor with a test lamp that is connected to battery positive.

Does the test light illuminate?

Go to Step 11

Go to Step 10

10 | Test blower motor speed control circuit for open, short to ground, short to voltage or for a high resistance. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 22 | Go to Step 16
11 | Test the ground circuit of blower motor control processor for open or a high resistance. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 22 | Go to Step 12
12 | Test the ground circuit between blower motor and the control processor for open, short to voltage or for a high resistance. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 22 | Go to Step 15
13 | Inspect for poor connections at the harness connector of the blower motor relay. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | Go to Step 22 | Go to Step 18
14 | Inspect for poor connections at the harness connector of the blower motor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | Go to Step 22 | Go to Step 19
15 | 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 . Did you find and correct the condition? | Go to Step 22 | Go to Step 20
16 | 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 . Did you find and correct the condition? | Go to Step 22 | Go to Step 21
17 | Repair the battery positive voltage circuit of the blower motor relay. Refer to Wiring Repairs . Is the trouble corrected? | Go to Step 22 | --
18 | Replace the blower motor relay. Have you finished the replacement? | Go to Step 22 | --
19 | Replace the blower motor. Refer to Blower Motor Replacement . Have you finished the replacement? | Go to Step 22 | --
20 | Replace the blower control processor. Refer to Blower Motor Control Module Replacement . Have you finished the replacement? | Go to Step 22 | --
21 | Replace the HVAC control module. Refer to Control Module References for replacement, setup, and programming. Have you finished the replacement? | Go to Step 22 | --
22 | Operate the system to verify the repair. Did you correct the condition? | System OK | Go to Step 2