Whenever we turn on the controls to our auto air conditioning unit we normally expect a cold breeze to come through the vents. This assumption depends upon the condition of our compressor, clutch assembly and amount of Freon the vehicle has in the condenser. We can become slightly irritated when the vents blow warm but stay secure in the knowledge that the system might require only a partial charge and, at the most, an evacuation and recharge. This slight irritation can turn to major frustration when we discover that the AC clutch has failed completely. Fortunately, a competent repair person can replace a defective AC clutch in a few simple steps.
- Skill level:
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Things you need
- Owner's repair manual
- Socket set
- Ratchet wrench
- Penetrating oil
- Air impact wrench
- Carburettor cleaner
- Gear puller
- Clutch assembly
- Torque wrench
Place the vehicle in park for an automatic transmission or neutral for the manual type. Set the emergency brake and raise the bonnet. Disconnect the negative battery from the battery terminal post with a socket and wrench. Refer to your owner's manual to locate the idle tensioner puller at the front of the engine. It holds tension on the serpentine belt by spring force.
Place a socket on the idler pulley nut and turn the wrench to relieve pressure on the belt. Note the routing orientation of the belt and then slip it off. Find the rear and front mounting bolts that hold the compressor to the engine bracket. Loosen and remove the bolts with a socket and wrench. Tilt up the front of the compressor and place a block of wood under it so that it clears the radiator shroud.
Spray the centre compressor hub nut and inner recess of the clutch hub with penetrating oil and let it soak for 15 minutes. Place an air impact wrench and socket on the hub nut and hit the trigger for counterclockwise rotation. Remove the outer hub. Place snap ring pliers inside the pulley and compress the large C-ring. Pull out the C-ring. Place a gear puller tool on the clutch pulley by placing the puller prongs over the edges of the pulley.
Screw the gear puller centre shaft bolt clockwise with a socket and wrench. Slide the pulley off the shaft and set it aside. Watch for any shims that came out with the unit and be ready to install them back into their original position. If the key remained in the keyway on the shaft, leave it positioned there. Clean the shaft and the inside of the coil area with some carburettor cleaner and a rag. Wipe it dry with a rag.
Place the new clutch assembly over the shaft, aligned with the shaft key. Reinsert any shims that sat behind clutch assembly. Tap the new clutch assembly back into its seat on the shaft with a hammer and a block of wood. Insert the C-ring back into its groove with the snap ring pliers. Place the outer hub back onto the shaft and screw the centre nut back on. Tighten the centre nut with a torque wrench according to your manual's specifications.
Remove the block of wood from underneath the compressor. Replace the front and rear compressor mounting bolts back into their bracket holes. Tighten the bolts with a socket and wrench. Place a socket and wrench on the idler pulley centre nut and turn the wrench so the pulley compresses. Slip the serpentine belt back onto the compressor pulley. If you have trouble with the belt routing, consult your manual for its configuration or check the routing emblem displayed on the fan shroud.
Reconnect the negative battery cable with a socket. Turn on the engine and set the AC controls on high. Listen for the new clutch to engage. Check the vents for cool air.
Tips and warnings
- Some vehicles require an air gap between the compressor coil and the clutch housing. You can measure this gap with a feeler gauge in the seam between the two components after installation. Consult your owner's manual for the recommended gap. You can add or subtract shims to meet the specifications.
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