A/C Pressure Sensor Fault (ATC)

AC PRESSURE SENSOR FAULT (ATC)

For a complete wiring diagram Consult Diagrams/Electrical

- When Monitored:
With the engine running and the A/C Relay energized.

- Set Condition:
If the A/C Heater Control receives the A/C Pressure Sensor Failed message from the Body Control Module (BCM).





NOTE: This DTC must be active for the results of this test to be valid. Do not perform this test if this DTC is stored. Refer to HVAC System Test (ATC) for stored DTC test procedures.

Diagnostic Test

1. CHECK FOR DTCs
Turn the ignition on.
With the scan tool, check for DTC's.
Does the scan tool display any DTCs?

Yes

- Diagnose and repair the DTC(s).
- Perform the BODY VERIFICATION TEST - VER 1. Body Verification Test.

No

- Go To 2

2. VERIFY REFRIGERANT SYSTEM IS PROPERLY CHARGED
Verify that the refrigerant system is properly charged.
Is the refrigerant system properly charged?

Yes

- Go To 3

No

- Recharge the refrigerant system.
- Run the Cooldown Test after the repair is complete.
- Perform BODY VERIFICATION TEST - VER 1. Body Verification Test.

3. PERFORM THE COOLDOWN TEST
NOTE: The following are prerequisites of the Cooldown Test. Verify each of the following before running the test:
- If active, diagnose and repair DTC Evap Temp Sensor Open or DTC Evap Temp Sensor Shorted before proceeding.
- Verify that the refrigerant system has an adequate charge. Check and repair as necessary before proceeding.
- Verify that the blower motor operates correctly in all speeds. Diagnose and repair all blower related faults before proceeding.
- Verify that the work area ambient temperature is above 13°C (55°F) before proceeding. Move the vehicle to a warmer work area if necessary.
- Verify that the evaporator temperature is above 13°C (55°F) before proceeding.
- Verify that the A/C compressor is not running. If the A/C compressor is running, turn the A/C off and allow the evaporator to warm up before proceeding.


Once all of the prerequisites have been met, start the engine and actuate the Cooldown Test with the scan tool.

NOTE: The Cooldown Test can take up to two minutes to run. While the test is running, the DELAY VF segment and A/C LED will flash. If the test fails, the VF segment and LED will continue to flash until either the vehicle is driven more than eight miles or a successful test is performed. When the test is complete, the scan tool will display one or more test status messages to indicate the outcome of the test. These messages will clear from memory, so note all messages before exiting the test.

Allow the test to run to completion before proceeding.
Does the scan tool display a status message that indicates a fault has occurred?

Yes

- Diagnose and Repair the fault(s).
- Run the Cooldown Test after the repair is complete.
- Perform the BODY VERIFICATION TEST - VER 1. Body Verification Test.

No

- Replace the A/C Heater Control.
- Perform BODY VERIFICATION TEST - VER 1. Body Verification Test.