Troubleshooting your York room air conditioner when evaporator fins are iced up
Your York room air conditioner won't cool well when its evaporator fins are iced up. The evaporator fins ice up if the compressor runs constantly for one of these reasons: a dirty air filter restricts air flow; the air conditioner is too small for the room; the temperature setting is too cold; a control is defective. See the repairs below to help correct a problem with evaporator finds that ice up.
What to do when the compressor is humming but not working in your York room air conditioner
If you turn York room 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.