Circuit Description
The HVAC control module commands the left air temperature actuator to move by controlling the voltage supplied on the control circuit. A low voltage of 0 volts moves door toward full hot. A voltage of 2.5 volts stops the door. A high voltage of 5 volts moves the door toward full cold. The HVAC control module determines the current position of the actuator by monitoring the voltage on the signal circuit. The feedback potentiometer is a function of the motor position. A high voltage of 4-5 volts indicates full cold door position. A low voltage of less than 1 volt indicates full hot door position. The HVAC control module controls the left air temperature actuator door positions in order to maintain the selected air temperature.
Conditions for Running the DTC
The ignition is turned ON.
Conditions for Setting the DTC
The HVAC control module detects the signal circuit is less than 5 counts (0.09 V).
Action Taken When the DTC Sets
A default value will be used for the sensor data by the HVAC control module in an attempt to maintain the air temperature selected by the driver.
Conditions for Clearing the DTC
| • | The DTC will become history if the HVAC control module no longer detects a failure. |
| • | The history DTC will clear after 100 fault free ignition cycles. |
| • | The DTC can be cleared with a scan tool. |
Diagnostic Aids
Check the following conditions:
A disconnected or broken door may also set this DTC by allowing the left air temperature actuator to travel to its internal stops (overtravel condition).
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.
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Tests for a default setting viewed by the scan tool.
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Tests for the proper operation of the circuit in the high voltage range.
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Tests for the proper operation of the circuit in the low voltage range. If the fuse in the jumper opens when you perform this test, the signal circuit is shorted to voltage.
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Tests for a short to ground in the 5 volt reference circuit.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
Schematic Reference: HVAC Schematics | ||||
1 | Did you perform the HVAC Diagnostic System Check? | -- | Go to Step 2 | |
2 |
Does the scan tool indicate that the LH Mix Mtr Position Feedback parameter is within the specified range? | 5-250 counts | Go to Step 3 | Go to Step 4 |
Place the air temperature switch from the warmest position to the coldest position. Does the scan tool indicate that the value of the LH Mix Mtr Position Feedback parameter remains near the specified value? | 127 counts | Go to Step 4 | Go to Diagnostic Aids | |
Is the voltage greater than the specified value? | 4.90 volts | Go to Step 5 | Go to Step 9 | |
Is the voltage less than the specified value? | 0.09 volts | Go to Step 6 | Go to Step 10 | |
Is the voltage greater than the specified value? | 4.90 volts | Go to Step 8 | Go to Step 7 | |
7 | Test the 5 volt reference circuit of the left air temperature actuator for a short to ground, or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 16 | Go to Step 13 |
8 | Test the 5 volt reference circuit of the left air temperature actuator for a short to voltage, a high resistance, or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 16 | Go to Step 12 |
9 | Test the signal circuit of the left air temperature actuator for a short to ground, or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 16 | Go to Step 13 |
10 | Test the signal circuit of the left air temperature actuator for a short to voltage, a high resistance, or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 16 | Go to Step 11 |
11 | Test the low reference circuit of the left air temperature actuator for a high resistance or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 16 | Go to Step 13 |
12 | Inspect for poor connections at the harness connector of the left 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 16 | Go to Step 14 |
13 | 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 16 | Go to Step 15 |
14 |
Important: Perform the recalibration procedure for the left air temperature actuator. Replace the left air temperature actuator. Refer to Air Temperature Actuator Replacement - Left Side . Did you complete the replacement? | -- | Go to Step 16 | -- |
15 |
Important: Perform the recalibration procedure for the HVAC control module. Replace the HVAC control module. Refer to HVAC Control Module Replacement . Did you complete the replacement? | -- | Go to Step 16 | -- |
16 |
Does the DTC reset? | -- | Go to Step 2 | System OK |
