Compressor Clutch Does Not Engage

HVAC COMPRESSOR CLUTCH DOES NOT ENGAGE

DIAGNOSTIC AIDS
The air conditioning (A/C) compressor clutch will not engage under the following conditions:
- The A/C high side line pressure is over 2 413 kPa (350 psi).
- The throttle angle is at 100 percent.
- A/C compressor temperature switch contacts are open.
- The engine speed is more than 5,500 RPM.
- The engine coolant temperature (ECT) is more than 123°C (253°F).
- The evaporator core temperature is less than 0°C (32°F).
- The engine is idling at a low unstable RPM.

TEST DESCRIPTION

Steps 1 - 7:

Steps 8 - 19:

Steps 20 - 32:

The numbers below refer to the step numbers on the diagnostic table.
2. The A/C compressor output is disabled if the engine is idling at a low unstable RPM.
3. The A/C compressor relay output is disabled if the engine coolant temperature is above 123°C (253°F). The check gages indicator will illuminate at this temperature.
5. These actions will enable the A/C compressor to operate.
7. 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.