What Is Wrong With My Window Air Conditioner if It Isn't Blowing Out Cold Air?

Clogged Filter

• Air conditioners don't just blow cold air out into a room. Along with removing the water vapor from the air, air conditioners also suck the dust particles out of the room's air. The filter on a window air conditioner is fairly small and will clog up pretty quickly with dirt and dust. A dirty filter will impede the unit's performance, and can cause it to blow out hot air. Follow the manufacturer's instructions to remove and clean the filter, and do so on a regular basis. The filter is normally located behind the grille located on the front of the unit.

Dirty Coils

• The unit's inner evaporator coils are located behind the front grille, inside the portion of the unit that hangs within the room. The inner condensing coils are located on the end that hangs outside. Dirt and dust can cling to wet coils. This blocks the flow of air, and, as a result, the system can't provide the proper cool air. Unplug the air conditioner, remove the front grille and slide the unit forward, far enough out of the cabinet that encases the inner components to allow you access to the coils. You can also remove the unit's cover and slide it forward. Vacuum the coils clean, but be sure not to collapse the fins.

Low Refrigerant

• If the air conditioner unit uses a refrigerant for cooling, the refrigerant may be low. This is often because of a refrigerant leak. This repair is better left up to a professional air conditioning technician who thoroughly understands how to fix the leak and service the unit. Special tools are needed to access the sealed refrigerant, and federal laws also regulate the handling of the refrigerant.

Additional Possibilities

• There are other potential causes when a window air conditioning unit does not blow out cold air. A simple solution may be removing a cover that you placed on the outside portion of the unit during the winter, and never removed. If you use the air conditioner when the outside temperature is too low, such as below 70 degrees Fahrenheit, ice can form on the evaporator. Avoid running the unit until the outside temperature rises. Also, if the unit's thermostat is already on the proper setting, a defective thermostat may be interfering with its cooling. In this case, you'll need to replace the thermostat. If the condenser fan, which blows hot air to the outside, is loose, unplug the unit and remove the grille, then tighten the fan.