For 1990-2009 cars

### Circuit Description

The HVAC door actuator is an electronic motor with a feedback potentionmeter. The HVAC control module supplies power and ground to the actuator. The HVAC control module controls the direction of the actuator by changing the polarity of the control circuit. When the actuator reaches the desired position, voltage is removed from the control circuit. The HVAC control module determines the current position of the actuator by monitoring the feedback voltage of the door position signal circuit. The feedback potentiometer position is a function of the actuator position.

• | Air flow control 3 circuit refers to the front mode actuator

• | Air flow control 7 circuit refers to the recirc actuator.

• | Temperature control 1 circuit refers to the driver air temperature actuator

• | Temperature control 2 circuit refers to the passenger air temperature actuator

• | Temperature control 3 circuit refers to the rear air temperature actuator

• | Air flow control 10 circuit refers to the rear mode actuator

### DTC Descriptors

This diagnostic procedure supports the following DTCs:

• | DTC B0248 Air Flow Control 3 Circuit

• | DTC B0268 Air Flow Control 7 Circuit

• | DTC B0408 Temperature Control 1 Circuit

• | DTC B0418 Temperature Control 2 Circuit

• | DTC B0428 Temperature Control 3 Circuit

• | DTC B3531 Air Flow Control 10 Circuit

This vehicle has DTCs which include DTC Symptoms. For more information on DTC Symptoms, refer to DTC Symptom Description .

DTC Symptom | DTC Symptom Descriptor
--- | ---
61 | Actuator Stuck

### Conditions for Running the DTC

• | The ignition is ON.

• | Ignition voltage is between 9-16 volts.

### Conditions for Setting the DTC

The actuator door movement is restricted or the actual door position differs from the commanded door position by 4 counts or greater for more than 16 seconds.

### Action Taken When the DTC Sets

The HVAC control module will not command actuator movement past the point where the stall condition is detected and will continue to make use of the remaining non-restricted range.

### Conditions for Clearing the DTC

• | The DTC will become history if the HVAC control module no longer detects the condition that set the DTC.

• | The history DTC will clear after 50 fault-free ignition cycles.

• | The DTC can be cleared with a scan tool.

### Test Description

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

1. This step verifies that the HVAC control module is able to command the appropriate HVAC actuator.

Step | Action | Values | Yes | No
--- | --- | --- | --- | ---
Schematic Reference: HVAC Schematics Connector End View Reference: HVAC Connector End Views
1 | Have you conducted Diagnostic System Check - Vehicle? | -- | Go to Step 2 | Go to Diagnostic System Check - Vehicle
2 |

1. Install a scan tool.
2. Turn ON the ignition, with the engine OFF.
3. With a scan tool, command the appropriate actuator in both directions.

Does the actual parameter of the appropriate actuator change?

--

Go to Step 3

Go to Step 4

3 | Is the voltage difference between the actual parameter and the commanded parameter of the appropriate actuator less than the specified value? | 0.3V | Go to Step 7 | Go to Step 6
4 |

1. Turn OFF the ignition.
2. Disconnect the actuator connector.
3. Turn ON the ignition.
4. Turn ON the HVAC module.
5. Connect a test lamp between the two driver circuits.
6. Command the actuator in both directions.

Does the test lamp illuminate then turn OFF in both directions?

--

Go to Step 13

Go to Step 5

5 | Test the control A circuit and control B circuit of the appropriate actuator for the following:

• | An open circuit

• | A high resistance

• | A short to ground

• | A short to voltage

Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

--

Go to Step 17

Go to Step 15

6 | Inspect the appropriate HVAC door and appropriate HVAC actuator for the following conditions:

• | A misaligned HVAC actuator

• | Broken or binding linkages or door

• | An obstruction that prevents the door from operating within its full range of motion

Did you find and correct the condition?

--

Go to Step 17

Go to Step 13

7 |

1. Turn OFF the ignition.
2. Unplug the appropriate actuator.
3. Turn ON the ignition.
4. Turn ON the HVAC control module.
5. Using a DMM measure the 5-volt reference.

Does the volt meter display near the specified value?

5V

Go to Step 8

Go to Step 12

8 | Using a DMM measure the signal circuit. Does the DMM display near the specified value? | 5V | Go to Step 9 | Go to Step 11
9 | Connect a DMM between the 5-volt reference circuit and the low reference circuit. Does the DMM display near the specified value? | 5V | Go to Step 13 | Go to Step 10
10 | Test the low reference circuit of the appropriate actuator for the following:

• | An open circuit

• | A short to voltage

• | A high resistance

Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

--

Go to Step 17

Go to Step 15

11 | Test the signal circuit of the appropriate actuator for the following:

• | An open circuit

• | A high resistance

• | A short to ground

• | A short to voltage

Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

--

Go to Step 17

Go to Step 15

12 | Test the 5-volt reference circuit of the appropriate actuator for the following:

• | An open circuit

• | A high resistance

• | A short to ground

• | A short to voltage

Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

--

Go to Step 17

Go to Step 15

13 | Inspect for poor connections at the harness connector of the appropriate HVAC actuator. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | -- | Go to Step 17 | Go to Step 14
14 | Replace the appropriate HVAC actuator. Refer to the appropriate replacement procedure:

• | Mode Actuator Replacement

• | Temperature Valve Actuator Replacement - Right Side

• | Temperature Valve Actuator Replacement - Left Side

• | Recirculation Actuator Replacement

• | Auxiliary Temperature Valve Actuator Replacement

• | Mode Actuator Replacement - Console

Have you finished the replacement?

--

Go to Step 17

--

15 | 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 17 | Go to Step 16
16 | Replace the appropriate HVAC control module. Refer to Control Module References for replacement, setup, and programming. Have you finished the replacement? | -- | Go to Step 17 | --
17 |

1. Use the scan tool in order to clear the DTCs.
2. Operate the vehicle within the Conditions for Running the DTC, as specified in the supporting text.

Does the DTC reset?

--

Go to Step 2

System OK