Circuit Description
The HVAC control processor monitors the inside air temperature through an inside air temperature sensor. When the air is cold, the sensor resistance and the signal voltage are high. When the air is warm, the sensor resistance and the signal voltage are low. The HVAC control processor maintains the selected air temperature by performing the following functions:
| • | Requesting engagement of the A/C compressor clutch |
| • | Controlling the door position of the air temperature actuator |
Conditions for Running the DTC
The ignition is turned ON.
Conditions for Setting the DTC
The HVAC control processor detects the signal circuit is more than 250 counts (4.90 volts).
Action Taken When the DTC Sets
A default value will be used for the sensor data by the HVAC control processor. The scan tool displays the default In Car Temperature sensor value in the Heating and Air Conditioning data list. The scan tool displays the actual Raw Inside Temperature value in the Heating and Air Conditioning Open/Short data list.
Conditions for Clearing the DTC
| • | The DTC becomes history if the HVAC control processor no longer detects a condition. |
| • | The history DTC clears after 50 fault-free ignition cycles. |
| • | The DTC can be cleared with a scan tool. |
Diagnostic Aids
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.
-
Tests for the proper operation of the circuit in the high voltage range.
-
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.
Step | Action | Yes | No |
|---|---|---|---|
Schematic Reference: HVAC Schematics | |||
1 | Did you perform the HVAC Diagnostic System Check? | Go to Step 2 | |
2 |
Does the scan tool display Open or Short? | Go to Step 3 | Go to Diagnostic Aids |
Does the scan tool display Open? | Go to Step 5 | Go to Step 4 | |
Does the scan tool display Short? | Go to Step 6 | Go to Step 8 | |
5 | Test the signal circuit of the inside air temperature sensor for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 12 | Go to Step 9 |
6 | Test the signal circuit of the inside air temperature sensor 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 12 | Go to Step 7 |
7 | Test the low reference circuit of the inside air temperature sensor 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 12 | Go to Step 9 |
8 | Inspect for poor connections at the harness connector of the inside air temperature sensor. 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 12 | Go to Step 10 |
9 | Inspect for poor connections at the harness connector of the HVAC control processor. 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 12 | Go to Step 11 |
10 | Replace the inside air temperature sensor. Refer to Inside Air Temperature Sensor Replacement . Did you complete the replacement? | Go to Step 12 | -- |
11 |
Important: Perform the recalibration procedure for the HVAC control processor. Replace the HVAC control processor. Refer to HVAC Control Processor Replacement . Did you complete the replacement? | Go to Step 12 | -- |
12 |
Does the DTC reset? | Go to Step 2 | System OK |
