Window Air Conditioner: Compressor humming but not working

If you turn the air conditioner off and then back on too quickly, the pressure of the refrigerant gas rises too high; as a result, the compressor hums and won’t start until the refrigerant pressure equalizes between the evaporator and condenser coils. Once you turn the air conditioner off, leave it off for several minutes before restarting it. Other reasons the compressor is humming but not starting include a dirty or otherwise restricted condenser coil or the short cycling of the compressor.

These repairs may help solve your Window Air Conditioner problem:

Replace the window air conditioner compressor


The compressor is a pump that compresses the refrigerant—Freon—that’s sealed in the window air conditioner. If the compressor doesn’t run when activated, have a refrigerator service technician replace it; by law, an EPA-licensed technician must do this repair because it involves Freon.

For manuals, repair guides, and specific part recommendations, enter your model number.

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