Why Does an Air Conditioner Not Work Properly?

Blocked Filter

• If the internal air filter of the air conditioner is clogged or blocked, the unit might not blow cold air or any air at all. The air filter in some units is reusable and washable. To remove the filter pull open the unit's front or back grille with your hands, and pull the filter out of its slot. If the filter is dirty, run warm water over both sides of the filter until all dirt, dust and other blockage disappears. Lay the filter out to dry, or blot it dry with a towel. Reinsert the filter and close the grille.

Blocked Vents

• Blockage, created by curtains or furniture, can prevent the air from entering or exiting the air conditioner. Remove curtains fully from the front of the air conditioner window units. A curtain hanging in front of the air conditioner grille will prevent air from circulating through the unit and might damage the unit. Curtains hanging in front of the louvers or vents prevent air from blowing out into the room. Remove couches, chairs or tables from the vents of the unit.

Power Failure

• When the unit experiences an electrical surge or lightning strike, it sometimes fails to turn back on. Unplug the unit's power cord from the wall outlet and allow the unit to sit for at least two minutes. While you wait, locate the breaker box and the breaker that controls the air conditioner. Inspect the position of the breaker switch. If the switch is in the middle or "Off" position, flip the switch back over to "On." Plug the unit back into the wall, and press the "Reset" button on the plug. Allow three minutes to pass before you turn the unit on.

Incorrect Mode

• Warm air blowing from a unit could be the result of the mode being incorrectly set to "Fan Only" instead of "Cool" mode. Press the "Mode" button on the remote control or on the unit's front panel repeatedly until the "Cool" mode indicator light illuminates. Press the down directional buttons to lower the thermostat until you feel cold air blow from the louvers.

Timer Failure

• You might have skipped over the final step of timer scheduling if the timer was set but fails to deactivate the unit when scheduled. To complete and enable the timer function, the "Set" button must be pressed. If a "Set" button doesn't exist, press the "Timer" button again after the designated time has been set.