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How to Replace a Car Air Conditioning (AC) Compressor

an A/C compressor

The compressor is designed to pump refrigerant through the A/C system and to convert low pressure vapor refrigerant into high pressure vapor refrigerant. All modern compressors utilize a clutch and drive pulley. The pulley is driven off a drive belt whenever the engine is running. When the A/C button is pushed the clutch is engaged, locking the compressor to the pulley, causing it to turn.

If the compressor has failed, the A/C system will not work. A compressor that is seized may also contaminate the rest of the A/C system with metal debris.

Part 1 of 2: Locate the compressor

locating the A/C compressor

Step 1: Locate the A/C compressor. The A/C compressor will be located at the front of the engine with the rest of the belt-driven accessories.

a mechanic evacuating the system

Step 2: Have the refrigerant recovered by a professional. Before the A/C system can be serviced, the refrigerant must be removed from the system.

This can only be done by a professional using an evacuation machine.

Part 2 of 2: Remove the compressor

  • Jack and jack stands
  • Protective gloves
  • Repair manuals
  • Safety glasses
  • Wrench

  • Note: Be sure to wear protective gloves and safety glasses before working.

locating the serpentine belt tensioner

Step 1: Locate the serpentine belt tensioner. If you have a difficult time finding the tensioner, consult the belt routing diagram.

This can typically be found on a decal placed somewhere in the engine compartment, or in the vehicle repair manual.

rotate the tensioner

Step 2: Rotate the tensioner. Use a socket or wrench to slide the automatic tensioner away from the belt.

Whether this is clockwise or counterclockwise depends on the vehicle and belt routing.

  • Note: Some tensioners will have a square hole to insert a ratchet end into, rather than a bolt head for a socket or wrench.

removing the belt from the pulleys

Step 3: Remove the belt from the pulleys. While holding the tensioner away from the belt, slide the belt off the pulleys.

disconnecting the compressor electrical connectors

Step 4: Disconnect the electrical connectors from the compressor. These should pull out easily.

disconnecting the pressure hoses

Step 5: Disconnect the pressure hoses from the compressor. Using a ratchet or wrench, disconnect the pressure hoses from the compressor.

Plug them to prevent system contamination.

removing the compressor mounting bolts

Step 6: Remove the compressor mounting bolts. Using a ratchet or wrench, remove the compressor mounting bolts.

removing the compressor from the vehicle

Step 7: Remove the compressor from the vehicle. It should come out with a little tugging, but be careful because it is often heavy.

adding oil to the compressor

Step 8: Prepare the new compressor. Compare the new compressor to the old one to ensure they are the same.

Then remove the dust caps from the new compressor and add a small amount of recommended lubricant to the new compressor (usually around ½ ounce). Most compressors use PAG oil, but a few use Polyol Glycol, so it’s important to determine which is used in your vehicle.

Also, some compressors come with the oil already installed; read the instructions supplied with your compressor.

replacing the old o-rings by sliding it off

Step 9: Replace the pressure line o-rings. Use a small screwdriver or pick to remove the o-rings from the A/C pressure lines.

Some compressors will come with replacement o-rings, or your can get replacements from your local auto parts store. Slide the new o-rings into place.

installing the compressor by lowering it into the vehicle

Step 10: Lower the new compressor into the vehicle. Lower the new compressor into the vehicle and align it with the mounting holes.

tightening down the mounting bolts

Step 11: Reinstall the mounting bolts. Reinstall the mounting bolts and tighten them down.

tightening the line bolts

Step 12: Reinstall the lines. Reinstall the lines and tighten down the bolts the line bolts.

reinstall the electrical connectors

Step 13: Reinstall the electrical connectors. Reinstall the electrical connectors as they originally were.

positioning the new belt on the pulleys

Step 14: Position the belt on the pulleys. Position the belt on the pulleys, following the belt routing diagram to ensure the belt is routed correctly.

pushing down on the tensioner and installing the belt

Step 15: Install the new belt. Push or pull the tensioner to a position that allows the belt to be installed onto the pulleys.

Once the belt is in place, you can release the tensioner and remove your tool.

Step 16: Have a professional recharge the system. Have the system recharged by a professional.

You should now have ice cold A/C - no more sweating through your clothes on a hot summer's day. Compressor replacement is not an easy task, though, so if you prefer to have a professional tackle this job for you, the team at YourMechanic offers top-notch compressor replacement.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
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