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Test Description

WARNING: This page is about a different car, the 2003 Oldsmobile Bravada, 2003 GMC Envoy XL, 2003 GMC Envoy, and 2003 Chevrolet TrailBlazer. However, it is still accessible from the selected car via links, so may be relevant.

The numbers below refer to the step numbers on the diagnostic table.

  1. 2. The A/C compressor relay output is disabled if engine coolant temperature is above 123°C (253°F). The engine coolant indicator will illuminate at this temperature.
  2. 3. This step ensures that the HVAC control module is receiving an input from the A/C switch.
  3. 4. These actions will enable the A/C compressor to operate.
  4. 5. This test ensures that there is sufficient refrigerant in the A/C system. The specific values come from the A/C System Performance Test in Heating, Ventilation and Air Conditioning.
  5. 7. The A/C low pressure switch parameter is out of range when the HVAC control module interprets the signal being below 151 kPa (22 psi) or above 275 kPa (40 psi).
  6. 8. This action will simulate a closed switch condition.
  7. If the Pressure Cycle Switch parameter reads Low Pressure than there is a circuit condition or a condition with the HVAC control module.
  8. 11. The A/C compressor relay output from the powertrain control module (PCM) is disabled if the A/C high side system pressure is interpreted to be higher than 2413 kPa (350 psi).
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