Automotive air conditioning compressors use an engine-driven pulley to circulate freon through the A/C system. These compressors require internal lubricant that can leak or wear out, damaging the compressor. Fixing this is not difficult, and the average backyard mechanic can replace a broken compressor in most vehicles in about two hours.
Evacuate the air conditioning system by taking the vehicle to an authorized freon collection facility. Do not vent the freon into the atmosphere. Most garages and oil change stations will collect this freon for free using professional equipment, because they get compensated for the freon they collect. It can also be recycled back into the system after the repair, but you should use fresh coolant to refresh the lubricants.
Disconnect the battery by turning the positive terminal counterclockwise. Set the terminal aside.
Remove the belt from the compressor pulley wheel by firmly pushing on the tension pulley arm and sliding the belt from the idle pulley if you have a serpentine belt system. Once the belt is free from the idle pulley, you can remove it from the grooved compressor pulley wheel. On single-belt systems, turn the adjustment bolt on the compressor mount counterclockwise until the compressor can slide. This releases tension on the belt, which can be taken from the pulley.
Disconnect the compressor from the wiring harness by pulling the adapter plug from the terminal on the compressor.
Remove the freon lines by turning their line bolts counterclockwise. Some hissing may occur, but with an evacuated system it should not be dangerous. Do not uncouple the lines on a pressurized system.
Remove the compressor by turning the mount bolts counterclockwise, then manipulating the unit from the mount arms.
Replace the compressor by positioning it into the mount arms and tightening the mount bolts.
Connect the freon lines by turning their line bolts clockwise until they are snug. Check the gaskets for wear before reconnecting the lines.
Replace the drive belt over the compressor pulley wheel. You can replace serpentine belts by looping the belt over the compressor pulley wheel, then pressing the tension pulley arm while sliding the belt underneath the idle pulley. When the tension pulley is released, the tension will pull the belt tight. On single-belt systems, position the belt over the pulley, then pull the compressor while tightening the adjustment bolt in a clockwise direction. The belt should have about 1/2 inch of play.
Reconnect the wiring harness by pressing the adapter plug into the terminal.
Reconnect the battery by turning the positive terminal bolt clockwise.
Refill the air conditioning system by using the freon kit, or taking the vehicle back to the garage to recycle the old freon. The freon fill kit plugs into the low-side nipple near the evaporator unit, and is filled with a valved can; consult the automobile's manual for specific procedures.
