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How Do I Replace a Compressor in a Window AC Unit?

Robert Moreschi

During the hot summer months, there is nothing worse than having to do without your window AC unit due to a faulty compressor. With the right supplies and know-how, it is possible for anyone to replace a rotary compressor, which is the type of compressor commonly found in window AC units.

The compressor in a window AC unit is fairly easy to replace.
  1. Shut off the power to the unit and recover the system's refrigerant by marking the leads on the storage cylinder and removing them from the AC unit. This step is required for compliance with Environmental Protection Agency regulations.

  2. Locate where copper wires connect the inlet and outlet and cut them loose from the old compressor.

  3. Remove the mounting bolts from the base of the old compressor, and then remove the old compressor from the unit.

  4. Place the new compressor into the AC unit and fasten it in with the mounting bolts that were holding in the previous compressor.

  5. Braze the copper lines to the inlet and outlet of the new compressor. Using a wire brush, first clean out the copper lines to remove any debris and then apply flux to the ends of the each line using a small paintbrush. Then braze the copper lines using an acetylene torch. Use a reduced flame and keep the torch concentrated over the ends of the copper lines to ensure that they are bonded properly with the inlet and outlet.

  6. Pressurize the new compressor with dry nitrogen after the unit has been sealed, and check for any leaks.

  7. Connect a vacuum pump to the unit and evacuate any liquids or excess refrigerant. Leave the pump running for a few hours to make sure that everything is evacuated properly.

  8. Reconnect the electrical wires to the air conditioning unit and then remove the vacuum pump.

  9. Add refrigerant back into the unit and then power it back on to get the proper amount of refrigerant circulating back into the system.