GM Service Manual Online
For 1990-2009 cars only

Step

Action

Yes

No

Schematic Reference: HVAC Schematics

DEFINITION: The outside air temperature display is inaccurate with no DTC set.

1

Did you perform the HVAC Diagnostic System Check?

Go to Step 2

Go to Diagnostic System Check - HVAC Systems - Automatic

2

  1. Turn OFF the ignition.
  2. Disconnect the ambient air temperature sensor.
  3. Test the resistance of the ambient air temperature sensor. Refer to Sensor Resistance Table .

Is the resistance measurement near the value in the sensor resistance table?

Go to Step 3

Go to Step 5

3

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 7

Go to Step 4

4

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 7

Go to Step 6

5

Replace the ambient air temperature sensor. Refer to Ambient Air Temperature Sensor Replacement .

Did you complete the replacement?

Go to Step 7

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6

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 7

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7

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 2