Circuit Description
The HVAC control module receives a position signal from the air temperature actuator. The air temperature actuator position sensor is a potentiometer that is tied to a 5 V reference source. The variable output from the potentiometer feeds back a position signal to a pull-up resistor which is located in the HVAC control module. This signal determines the necessary drive signal to the actuator motor which provides the proper air temperature door position. This value is stored in the Keep Alive Memory (KAM) portion of the HVAC control module. When the air temperature door is in a full hot position the scan tool will read above 190 Counts. When the air temperature door is in full cold position the scan tool will read below 48 Counts. Normal operating range is 46 Counts to 194 Counts.
Conditions for Running the DTC
The ignition is in the ON position.
Conditions for Setting the DTC
The HVAC control module detects this condition when the ignition switch is in the ON position and one or more of the following conditions exists:
| • | Ignition 3 voltage is open. |
| • | The air temperature actuator signal circuit is shorted to voltage, ground, or open. |
| • | The 5 V air temperature door control circuit is shorted to voltage, ground, or open. |
| • | The 5 V reference is shorted to voltage, ground, or open. |
| • | Low reference is open. |
The HVAC control module does not sense the expected change in the temperature door position when the air temperature valve sensor and motor is commanded to move the temperature valve.
Action Taken When the DTC Sets
The HVAC control module drives the temperature valve to the full COLD position when the system is in one of the following modes:
| • | PANEL |
| • | BI-LEVEL |
| • | AUTO PANEL/AUTO BI-LEVEL |
The HVAC control module drives the temperature valve to full HEAT position when the system is in one of the following modes:
| • | LOWER |
| • | DEFOG |
| • | DEFROST |
| • | AUTO LOWER |
Conditions for Clearing the DTC
| • | The DTC becomes history when the HVAC control module no longer detects a failure. |
| • | The history DTC clears after 50 fault-free ignition cycles. |
| • | The DTC can be cleared with a scan tool. |
Diagnostic Aids
| • | Normal operating range is 40 Counts to 200 Counts. If out of this range check for binding, misalignment, or broken air temperature door. |
| • | If condition is not present refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems. |
Test Description
The number(s) below refer to the step number(s) on the diagnostic table.
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Test for other DTC that are current DTC that could also set this DTC but would need to be diagnosed first.
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Tests for the proper operation of the circuit to insure that commanded and actual positions are within specifications.
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Tests for the proper operation of the circuit when door is commanded to move.
Step | Action | Value(s) | Yes | No | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
1 | Did you perform the HVAC Diagnostic System Check? | -- | Go to Step 2 | Go to Diagnostic System Check | ||||||
Does the scan tool indicate that DTC B0415 or B0416 set along with B0408? | -- | Go to DTC Table | Go to Step 3 | |||||||
Does the scan tool indicate that the Air Mix Door Commanded data parameter is within the specified value of the Air Mix Door Actual data parameter? | 0-3 counts | Go to Diagnostic Aids | Go to Step 4 | |||||||
Does the Air Mix Door Actual data parameter change at all? | -- | Go to Step 10 | Go to Step 5 | |||||||
5 | Test the ignition 3 voltage circuit of the air temperature actuator for an open or a high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 15 | Go to Step 6 | ||||||
6 | Test the 5 volt reference 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 15 | Go to Step 7 | ||||||
7 | Test the air temperature door control 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 15 | Go to Step 8 | ||||||
8 | Test the air temperature actuator ground for open, or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 15 | Go to Step 9 | ||||||
9 |
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 12 | Go to Step 10 | ||||||
10 | Inspect the air temperature door and the air temperature actuator for the following:
Did you find and correct the condition? | -- | Go to Step 15 | Go to Step 11 | ||||||
11 | Inspect for poor connections at the harness connector of the air temperature actuator. Refer to Testing for Intermittent Conditions and Poor Connections and Special Tools in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 15 | Go to Step 13 | ||||||
12 | Inspect for poor connections at the harness connector of the HVAC control module. Refer to Testing for Intermittent Conditions and Poor Connections and Special Tools in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 15 | Go to Step 14 | ||||||
13 |
Important:: Perform the recalibration procedure for the air temperature actuator. Replace the air temperature actuator. Refer to Temperature Actuator Replacement in Heating Ventilation and Air Conditioning. Did you complete the replacement? | -- | Go to Step 15 | -- | ||||||
14 | Replace the HVAC control module. Refer to Control Assembly Replacement . Did you complete the replacement? | -- | Go to Step 15 | -- | ||||||
15 |
Does the DTC reset? | -- | Go to Step 2 | System OK |
