For 1990-2009 cars

Step | Action | Yes | No
--- | --- | --- | ---
Schematic Reference: HVAC Schematics Connector End View Reference: HVAC Connector End Views DEFINITION: Air recirculation is inoperative or is always ON.
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. Place the blower motor switch in each speed position.

Does blower motor run in the desired speed position?

Go to Testing for Intermittent Conditions and Poor Connections

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. Connect a test lamp between the blower motor supply voltage circuit and blower motor fan control circuit.
5. Turn the blower motor switch from the min. speed position to the max. speed position.

Does the test lamp illuminate and the lightness increase?

Go to Step 9

Go to Step 4

4 |

1. Turn OFF the ignition.
2. Disconnect the blower control processor.
3. Turn ON the ignition, with the engine OFF
4. Probe the speed control circuit of the blower motor at the connection of blower motor control processor with a test lamp which is connected to battery voltage.
5. Turn the blower motor switch from the min. speed position to the max. speed position.

Does the test lamp illuminate and the lightness increase?

Go to Step 6

Go to Step 5

5 | Test the speed control circuit of blower motor in HVAC control module for a high resistance. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 15 | Go to Step 11
6 | Test battery position circuit of blower motor control processor for a high resistance. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 15 | Go to Step 7
7 | Test the ground circuit of blower motor control processor for a high resistance. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 15 | Go to Step 8
8 | Test fan control circuit of blower motor control processor for a high resistance. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 15 | Go to Step 10
9 | 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 15 | Go to Step 12
10 | 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 15 | Go to Step 13
11 | 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 15 | Go to Step 14
12 | Replace the blower motor. Refer to Blower Motor Replacement . Have you finished the replacement? | Go to Step 15 | --
13 | Replace the blower control processor. Refer to Blower Motor Control Module Replacement . Have you finished the replacement? | Go to Step 15 | --
14 | Replace the HVAC control module. Refer to Control Module References for replacement, setup, and programming. Have you finished the replacement? | Go to Step 15 | --
15 | Operate the system to verify the repair. Did you correct the condition? | System OK | Go to Step 2