Operation CHARM: Car repair manuals for everyone.

B0179

Steps 1-5:




Steps 6-12:




CIRCUIT DESCRIPTION
The HVAC control module monitors the air temperature in the floor discharge duct via a temperature sensor. When the air is cold, the sensor resistance and signal voltage are high. When the air is warm, the sensor resistance and signal voltage are low.

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 V (5 counts) or greater than 4.90 V (250 counts).

ACTION TAKEN WHEN THE DTC SETS
A default value of 2.50 V (127 counts). Will be used for the sensor data by the HVAC control module. The sensor reading displayed on the scan tool in the HVAC data list will be this default.

CONDITIONS FOR CLEARING THE DTC
- The DTC will become history if the HVAC control module no longer detects a failure.
- The history DTC will clear after 50 fault free ignition cycles.
- The DTC can be cleared with a scan tool.

DIAGNOSTIC AIDS
Check the following conditions:
- Visually inspect the sensor for contamination or damage.
- Verify that air flow to sensor is not restricted.
- Verify that the sensor is installed properly.
- Refer to Testing for Intermittent and Poor Connections in diagrams.

TEST DESCRIPTION
The number(s) below refer to the step number(s) on the diagnostic table.
8. Tests for the possibility of a short to another 5 V reference circuit.