Circuit Description
The air temperature actuator is an electronic device that incorporates a stepper motor and a feedback potentiometer. The HVAC control module determines the position of the air temperature actuator that is based on the voltage from the potentiometer. When the keep alive RAM memory, the battery positive voltage circuit, of the HVAC control module is interrupted, the module will calibrate the actuators. The HVAC control module performs a travel range comparison of the determined values of the actuator to the calibrated values within the HVAC control module. If the determined range does not equal the calibrated expected range, the actuator will be considered not calibrated, and the DTC will set. The HVAC control module will also perform a continuous test on the current feedback value. If the feedback value does not fall within the calibrated range, the DTC will set.
Conditions for Running the DTC
| • | The ignition is ON. |
| • | Ignition voltage is between 9-16 volts. |
| • | The battery positive voltage circuit, which provides keep alive RAM memory power, of the HVAC control module must be interrupted in order to run the recalibration. This includes disconnecting the battery, removal of the Radio fuse and disconnecting the HVAC control module. |
Conditions for Setting the DTC
| • | The position signal of the air temperature door is out of the range 0.09-4.0 volts (5-250 counts). |
| • | The total travel range of the air temperature actuator falls without the calibrated limits. |
Action Taken When the DTC Sets
| • | The HVAC control module will continue to make use of whatever travel range is still available. |
| • | Each time the ignition switch is turned ON, the HVAC control module retests the actuator travel range. |
Conditions for Clearing the DTC
| • | If the HVAC control module no longer detects a condition, then the DTC will become history. |
| • | The history DTC will clear after 50 ignition cycles without a condition. |
| • | The DTC can be cleared with a scan tool. |
Diagnostic Aids
| • | The range fault can only be detected following a recalibration. The recalibration can only be initiated by removing the battery positive voltage circuit to the HVAC control module. |
| • | The calibration limit is 64-216 counts. An actual range below this limit suggests an obstruction, something stuck in the door which limits travel. An actual range above this limit suggests an excessive travel condition, damaged, or missing foam seals. |
| • | A damaged air temperature door or a damaged actuator can cause this DTC to set. |
| • | An intermittent short to ground on the HVAC class 2 serial data circuit can set this DTC. Recalibrate actuators and test system. |
| • | If the condition is not present, refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
Step | Action | Values | Yes | No | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
Schematic Reference: HVAC Schematics | ||||||||||
1 | Did you perform the HVAC Diagnostic System Check? | -- | Go to Step 2 | |||||||
Does the result of the calculation indicate that the actual travel of the air temperature actuator is within the specified range? | 64-216 Counts | Go to Step 3 | Go to Step 8 | |||||||
3 |
Does the scan tool indicate that the Air Mix Door Actual data parameter is within the specified range? | 5-250 Counts | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | Go to Step 4 | ||||||
4 | Test the ground circuit of the air temperature actuator for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 5 | ||||||
5 | Test the 5 volt reference circuit of the air temperature actuator for a short to ground or short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 6 | ||||||
6 | Test the air temperature door position signal circuit of the air temperature actuator for an open, high resistance, short to ground or short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 7 | ||||||
7 |
Important:: The air temperature actuator connector and the HVAC control module connector must be connected to correctly perform test.
Does the air temperature actuator drive shaft rotate and do the counts change? | -- | Go to Step 10 | Go to Step 9 | ||||||
8 | Inspect the air temperature door and the air temperature actuator for the following:
Did you find and correct the condition? | -- | Go to Step 13 | Go to Diagnostic Aids | ||||||
9 | Inspect for poor connections at the harness connector of the air temperature actuator. 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 13 | Go to Step 11 | ||||||
10 | 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 in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 12 | ||||||
11 |
Important:: Perform the recalibration for the air temperature actuator. Replace the air temperature actuator. Refer to Air Temperature Actuator Replacement . Did you complete the replacement? | -- | Go to Step 13 | -- | ||||||
12 |
Important:: Perform the recalibration for the HVAC control module. Replace the HVAC control module. Refer to HVAC Control Module Replacement . Did you complete the replacement? | -- | Go to Step 13 | -- | ||||||
13 |
Does the DTC reset? | -- | Go to Step 2 | System OK | ||||||
