Pinpoint Test 19: The Air Conditioning (A/C) Is Always On

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PINPOINT TEST 19: THE AIR CONDITIONING (A/C) IS ALWAYS ON - HYBRID

See the Tribute Wiring Diagram for schematic information.

Normal Operation

When A/C is requested, a message is sent from the HVAC module over the MS-CAN bus to the IC, then from the IC through the HS-CAN bus to the PCM.When an A/C request is received from the HVAC module, an A/C demand message is sent from the PCM over the HS-CAN bus to the Air Conditioning Compressor Module (ACCM) if all of the following conditions are met:

- The PCM does not detect excessively high or low refrigerant pressure from the A/C pressure transducer.
- The PCM does not detect excessively high engine coolant temperature.
- The PCM does not detect an ambient air temperature below -1°C (30°F).
- The PCM has not detected a Wide Open Throttle (WOT) condition.
- The HVAC module does not detect an evaporator discharge air temperature below 2°C (36°F).When the ACCM receives the A/C demand message, it will engage. Instead of cycling ON and OFF like a traditional A/C compressor, the PCM monitors the evaporator discharge temperature from the HVAC module to raise or lower the electric A/C compressor speed as required.

Possible Causes
- HVAC module
- Electric A/C compressor
- A/C evaporator discharge temperature sensor
- A/C pressure transducer

Diagnostic Procedure

NOTE:Diagnose any PCM, HVAC module or ACCM DTCs before carrying out the following pinpoint test.

Step 1-Step 3: