For 1990-2009 cars

Step | Action | Yes | No
--- | --- | --- | ---
Schematic Reference: HVAC Schematics Connector End View Reference: HVAC Connector End Views DEFINITION: The blower motor runs with HVAC controller when the blower motor is OFF, or the blower motor runs only when at a high speed.
1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle
2 |

1. Turn ON the ignition, with the engine OFF.
2. Turn OFF the HVAC Control Module.

Does the blower motor stop running?

Go to Step 3

Go to Step 8

3 |

1. Turn ON the HVAC Control Module.
2. Switch the blower motor switch from Min. to Max.

Does the blower motor run only when at a high speed?

Go to Step 4

Go to Blower Motor Malfunction

4 |

1. Turn OFF the ignition.
2. Unplug blower control processor.
3. Turn ON the ignition.
4. Turn ON the HVAC Control Module.
5. Probe the speed control circuit of the blower motor with a test lamp that is connected to battery positive.
6. Switch the blower switch from Min. to Max..

Does the test lamp lightness change?

Go to Step 6

Go to Step 5

5 | Test blower motor speed control circuit for short to ground. Refer to Circuit Testing and Wiring Repairs. Did you find and correct the condition? | Go to Step 11 | Go to Step 8
6 | Test blower motor fan control circuit for short to ground. Refer to Circuit Testingand Wiring Repairs. Did you find and correct the condition? | Go to Step 11 | Go to Step 7
7 | Inspect for poor connections at the harness connector of the blower motor control processor. Refer to Testing for Intermittent Conditions and Poor Connectionsand Connector Repairs. Did you find and correct the condition? | Go to Step 11 | Go to Step 9
8 | 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 11 | Go to Step 10
9 | Replace the blower control processor. Refer to Blower Motor Control Module Replacement . Have you finished the replacement? | Go to Step 11 | --
10 | Replace the HVAC control module. Refer to Control Module References for replacement, setup, and programming. Have you finished the replacement? | Go to Step 11 | --
11 | Operate the system to verify the repair. Did you correct the condition? | System OK | Go to Step 2