For 1990-2009 cars

### Test Description

The numbers below refer to the step numbers on the diagnostic table.

1. The measured voltage should be near the specified values for each mode position.

1. Two ignition 3 voltage circuits supply the HVAC control module. Test the ignition 3 voltage circuit that does not supply the blower motor switch.

Step | Action | Value | Yes | No
--- | --- | --- | --- | ---
Schematic Reference: HVAC Schematics Connector End View Reference: HVAC Connector End Views DEFINITION: Air does not flow correctly from the air distribution outlets.
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 the OFF position.

Is the blower motor OFF?

--

Go to Step 3

Go to Blower Motor Always On

3 | Place the blower motor switch in each speed position. Does the blower motor operate in any speed position? | -- | Go to Step 4 | Go to Blower Motor Inoperative
4 | Does the blower motor operate in each speed position? | -- | Go to Step 5 | Go to Blower Motor Malfunction
5 | Are all of the HVAC control module controls except for the blower motor inoperative? | -- | Go to Step 14 | Go to Step 6
6 |

1. Place the blower motor switch in the maximum speed position.
2. Place the mode switch in the vent position.
3. Place the recirculation switch in the ON position.
4. Observe the recirculation door.
5. Place the outside air switch in the ON position.

Does the recirculation door move from the recirculation to the outside air position?

--

Go to Step 7

Go to Air Recirculation Malfunction

7 |

1. Place the blower motor switch in the maximum speed position.
2. Place the mode switch in each mode position.

Does air flow sufficiently from the proper air distribution outlets for each selected mode position?

--

Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems

Go to Step 8

8 | Inspect the air delivery system for the following conditions:

• | A dirty HVAC air filter, if applicable

• | An obstruction to the airflow

• | Air leaks

• | Misaligned air ducts

Did you find and correct the condition?

--

Go to Step 21

Go to Step 9

9 | Inspect the mode door and the mode actuator for the following conditions:

• | A misaligned mode actuator

| Refer to Mode Actuator Replacement .

• | Broken or binding linkages or mode door

• | An obstruction that prevents the mode actuator from operating within the full range of motion

• | Missing seals to the mode door

• | Misaligned seals to the mode door

Did you find and correct the condition?

--

Go to Step 21

Go to Step 10

10 |

1. Turn OFF the ignition.
2. Disconnect the mode actuator.
3. Turn ON the ignition, with the engine OFF.
4. Probe the ignition 3 voltage circuit of the mode actuator with a test lamp that is connected to a good ground.

Does the test lamp illuminate?

--

Go to Step 11

Go to Step 18

11 | Test the ground circuit of the mode actuator for an open or for a high resistance. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 21 | Go to Step 12
12 |

1. Turn OFF the ignition.
2. Reconnect the mode actuator.
3. Turn ON the ignition with the engine OFF.
4. Measure the voltage from the mode door control circuit of the mode actuator to a good ground.
5. Observe the control circuit voltage of the mode door .
6. Place the mode switch in each mode position.

Does the voltage measure near the specified values for each mode position?

Vent: 12.0V, Bi-Level: 9.0V, Floor: 6.0V Mix-Blend: 3.0V, Defrost: 0.0V

Go to Step 16

Go to Step 13

13 | Test the mode door control circuit of the mode actuator for an open, a high resistance, a short to ground, or a short to voltage. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | --- | Go to Step 21 | Go to Step 17
14 | Test the ignition 3 voltage circuit of the HVAC control module for an open or for a high resistance. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 21 | Go to Step 15
15 | Test the ground circuit of the HVAC control module for an open or for a high resistance. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 21 | Go to Step 17
16 | Inspect for bad connections at the harness connector of the mode actuator. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 21 | Go to Step 19
17 | Inspect for bad connections at the harness connector of the HVAC control module. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 21 | Go to Step 20
18 | Repair the ignition 3 voltage circuit of the mode actuator. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 21 | --
19 | Replace the mode actuator. Refer to Mode Actuator Replacement . Did you complete the replacement? | -- | Go to Step 21 | --
20 | Replace the HVAC Control module. Refer to Heater and Air Conditioning Control Replacement . Did you complete the replacement? | -- | Go to Step 21 | --
21 | Operate the system in order to verify the repair. Did you correct the condition? | -- | System OK | Go to Step 8