GM Service Manual Online
For 1990-2009 cars only

Circuit Description

The HVAC control module monitors the passenger compartment inside air temperature through an inside air temperature sensor. The inside air temperature sensor is a integral part of the HVAC control module. 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.

DTC Descriptors

This diagnostic procedure supports the following DTCs:

    • DTC B0165 Passenger Compartment Temp Sensor 1 left Circuit Low
    • DTC B0166 Passenger Compartment Temp Sensor 1 left Circuit High

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 0.09 volt.
    • The HVAC control module detects the signal circuit is more than 4.9 volts.

Action Taken When the DTC Sets

    • The DTC is stored in DTC information.
    • The HVAC control module will continue to monitor the reference signal of the inside air temperature sensor.

Conditions for Clearing the DTC

    • The DTC will become history if the HVAC control module 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 .

Step

Action

Yes

No

Schematic Reference: HVAC Schematics

Connector End View Reference: HVAC Connector End Views

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle

2

  1. Turn ON the ignition, with the engine OFF.
  2. With a scan tool, observe the Vehicle DTC list. Refer to Diagnostic Trouble Code (DTC) List - Vehicle .

Does the scan tool indicate the DTC is current?

Go to Step 3

Go to Diagnostic Aids

3

Test the ignition 3 voltage circuit of the HVAC control module for an open or a high resistance. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step  7

Go to Step  4

4

Test the ground circuit of the HVAC control module for an open. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step  7

Go to Step  5

5

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 .

Did you find and correct the condition?

Go to Step 7

Go to Step 6

6

Replace the HVAC control module. Refer to Control Module References for replacement, setup, and programming.

Did you complete the replacement?

Go to Step 7

--

7

  1. Use the scan tool in order to clear the DTCs.
  2. Operate the vehicle according to the Conditions for Running the DTC.

Does the DTC set again?

Go to Step 2

System OK