Compressor HVAC: Testing and Inspection

ON-VEHICLE INSPECTION

1. Install manifold gauge set.
a. Close the HI and LO hand valves.
b. Connect the red charging hose to the discharge service valve of the compressor.
c. Connect the blue charging hose to the suction service valve of the compressor.
2. Run engine at fast idle.
3. Check compressor for following:
a. High pressure gauge reading is not low and low pressure gauge reading is not higher than normal.
b. Metallic sound.
c. Leakage from the shaft seal.
If any of the above checks are faulty, 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.

Testing Compressor Clutch Resistance:

c. Using an ohmmeter, measure the resistance of the stator coil between the clutch lead wire and ground.
If the resistance is not within tolerance, replace the coil. Standard resistance: at 20°C (68°F) 3.7 + 0.2 Ohms