Compressor Clutch: Testing and Inspection

A/C Compressor Clutch Check

1. Check the armature plate for discoloration, peeling, or other damage. If there is damage, replace the clutch set Service and Repair.

2. Check the rotor pulley bearing play and drag by rotating the rotor pulley by hand. Replace the clutch set with a new one if it is noisy or has excessive play/drag Service and Repair.

NOTE: The rotor pulley and the armature plate were mated at the factory by a burnishing operation. Always replace the pulley and the plate as a set. Replacing only one part of the clutch set will cause clutch slippage.






3. Measure the clearance between the rotor pulley (A) and the armature plate (B) all the way around. If the clearance is not within specified limits, remove the armature plate Service and Repair and add or remove shims as needed to increase or decrease clearance.





NOTE: The shims are available in four thicknesses: 0.1 mm, 0.2 mm, 0.4 mm, and 0.5 mm.






4. Check the thermal protector for continuity between A/C compressor clutch 3P connector terminals No. 1 and No. 3. If there is no continuity, replace the thermal protector Service and Repair.

NOTE: The thermal protector will have no continuity above 251 to 262 °F (122 to 128 °C). When the temperature drops below 240 to 219 °F (116 to 104 °C), the thermal protector will have continuity.






5. Release the field coil connector from the holder, then disconnect it. Check for continuity between A/C compressor clutch 3P connector terminal No. 2 and the 1P connector. If there is no continuity, replace the thermal protector Service and Repair.






6. Disconnect the field coil connector (A). Check resistance of the field coil. If resistance is not within specifications, replace the field coil Service and Repair.