For 1990-2009 cars

### Test Description

The number below refers to the step number on the diagnostic table.

1. The High speed blower motor control circuit is spliced to the Blower motor voltage supply circuit. A short to ground on the control circuits will open the HVAC Blower fuse. Be sure to check all the blower motor control circuits for a short to ground.

1. There are two ignition 3 voltage supply circuits going to the HVAC control assembly. Test the one that supplies the blower motor switch.

Step | Action | 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 - Manual
2 |

1. Turn ON the ignition, with the engine OFF.
2. Place the blower motor 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.
3. Turn ON the ignition, with the engine OFF.
4. Turn ON the blower motor.
5. Probe the blower motor supply voltage circuit of the blower motor with a test lamp that is connected to a good ground.

Does the test lamp illuminate?

Go to Step 5

Go to Step 4

4 | Test the blower motor supply voltage circuit for an open, short to ground or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 11 | Go to Step 6
5 | Test the blower motor ground circuit 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 11 | Go to Step 7
6 | Test the ignition 3 voltage supply circuit of the HVAC control assembly for an open, short to ground or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 11 | Go to Step 8
7 | Inspect for poor connections at 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 11 | Go to Step 9
8 | Inspect for poor connections at the HVAC control assembly. 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 11 | Go to Step 10
9 | Replace the blower motor. Refer to Blower Motor Replacement in Heating Ventilation and Air Conditioning. Did you complete the replacement? | Go to Step 11 | --
10 | Replace the HVAC control assembly. Refer to Heater and Air Conditioning Control Replacement . Did you complete the replacement? | Go to Step 11 | --
11 | Operate the system in order to verify the repair. Did you correct the condition? | System OK | Go to Step 2