Compressor HVAC: Testing and Inspection

ON-VEHICLE INSPECTION

1. Install manifold gauge set.
2. Run engine at fast idle.
3. Check compressor for following:
a. High pressure gauge reading is not lower and low pressure gauge reading is not higher than normal.
b. Metallic sound.
c. Leakage from shaft seal

If defects are found, repair the compressor.

4. Check magnetic clutch.
a. Inspect the pressure plate and the rotor for signs of oil.
b. Check the clutch bearings for noise and grease leakage.





c. Using an ohmmeter, measure the resistance of the stator coil between terminal 1 and ground.

Standard resistance: 3.4 - 3.8 Ohms at 2O°C (68°F)

If resistance is not as specified, replace the coil.





d. Connect the positive (+) lead from the battery to terminal 1, check that the magnetic clutch is energized.

If magnetic clutch is not energized, replace the coil.

CAUTION: Do not short the positive (+) lead wire on the vehicle, when applying battery voltage.





5. Inspect revolution detecting sensor using an ohmmeter. Measure the resistance between two terminals 2 and 3 of the sensor.

Standard resistance: 100 - 130 Ohms at 20°C (68°F)

If resistance is not as specified, replace the revolution detecting sensor.