Causes

• If your air conditioner unit freezes up during cold winter weather, the outside temperature is probably lower than 60 degrees Fahrenheit, the average AC's lowest possible cooling level. The air circulation through the unit during harsh winter climates might cause condensation, which then freezes on the cooling element and blocks cold air from blowing out of the unit. To avoid this phenomenon, turn the air conditioner cooling element off, open the AC vent and leave the fan on at a low or medium speed to circulate the outside air through the room.
  
  

Temperature

• To melt the ice off of the coils, raise the thermostat to its highest setting and allow the fan to run, which will cause warm air from the room to move through the unit and defrost the internal ice. Press the "+" button on the remote control or the unit's front panel to raise the thermostat to, preferably, 86 degrees Fahrenheit, which is an AC unit's common highest setting. If the air conditioner features a heating element, activate the "Heat" function, and set the thermostat to a high setting.
  
  

Fan Speed

• Increase the melting power of a high thermostat setting with a high fan speed. Press the "Fan" button or the "Mode" button on the unit's remote control or front panel until the "Fan High" or "Cool High" icon is illuminated, which causes the warm air produced by the high thermostat setting to circulate quickly through the frozen coils to thaw them rapidly. Allow 30 minutes for the cooling element to defrost, and then gradually lower the thermostat.
  
  

Power

• If you want to thaw the AC unit without leaving the controls on, turn the unit off and allow it to defrost naturally. Press the "On/Off" or "Power" button on the remote control or the AC's front panel to turn the unit off. The airflow stops and the indicator lights turn off. As a safety measure, unplug the unit from the wall outlet, and allow it 60 minutes to defrost completely before plugging it back in.