Diagnostic Aids
The HVAC control module receives outside air temperature information from the instrument panel cluster (IPC) via class 2 serial data. If the HVAC control module does not receive outside air temperate information due to a sensor malfunction or loss of serial data, the HVAC will use and display a default air temperature value. For further information refer to Air Temperature Description and Operation in HVAC Systems - Automatic.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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This step tests for a high resistance in the signal circuit and the ground circuit of the ambient air temperature sensor.
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DTCs may be set in the IPC when you perform this diagnostic table.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
Schematic Reference: Instrument Cluster Schematics | ||||
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information |
2 |
Does the temperature displayed on the DIC match the current room temperature within 2°C (3°F)? | -- | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | Go to Step 3 |
Important: Verify the J 33431-C Signal Generator and Instrument Panel Tester resistance settings with a DMM. Does the DIC display the correct value? | -- | Go to Step 6 | Go to Step 4 | |
4 | Test the ambient air temperature sensor signal circuit for a high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 10 | Go to Step 5 |
5 | Test the ground circuit of the ambient air temperature sensor for a high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 10 | Go to Step 7 |
6 | Inspect for poor connections at the harness connector of the ambient 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 10 | Go to Step 8 |
7 | Inspect for poor connections at the harness connector of the instrument panel cluster (IPC). 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 10 | Go to Step 9 |
8 | Replace the ambient air temperature sensor. Refer to Ambient Air Temperature Sensor Replacement in HVAC Systems - Automatic. Did you complete the replacement? | -- | Go to Step 10 | -- |
9 | Replace the IPC. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming. Did you complete the replacement? | -- | Go to Step 10 | -- |
Did you correct the condition? | -- | System OK | Go to Step 2 | |
