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My Air Conditioner Will Not Cool Below 77

Whitney Houston

A central or window unit air conditioner should be able to cool a room lower than 77 degrees Fahrenheit, unless the air conditioner thermostat limit is 77 degrees Fahrenheit, which is unlikely. The standard cooling limit is approximately 71 degrees Fahrenheit for most units, so a cooling problem might indicate dirty or broken components.

Low Air Flow

Air conditioner panels can be removed to access certain internal components.

If the airflow within the unit is low and the room or home doesn’t seem to dip below 77 degrees Fahrenheit, the filter could be to blame. A clogged or dirty filter not only prevents the unit from efficiently taking in air through the intake grille, it also runs up the electric bill. You can open the intake grille to get to the air filter. When you pull the air filter out of its slot, you might confirm that the filter was inserted correctly. If a filter is to be inserted a certain way, the filter should feature indicators on the front or sides of the unit. To clean the air filter, you can use a vacuum or running water. Some air filters require complete replacement and not cleaning.


Items, such as drapes and furniture, in front of wall or ceiling vents prevent cool air from entering the room in order to meet the thermostat requirement. In like fashion, blockage in front of the outside unit prevents air from circulating through the unit and cooling the home. If you feel that cool air isn’t circulating through the home or a room properly, then you might inspect the state of all vents inside and outside of the home. Any blockage in or around the vents should be removed to allow air to flow freely through the unit.

Ice Buildup

Ice buildup could occur inside the system due to a problem with the condenser fan. If the fan is unable to spin freely and at full power, then the cold air generated by the cooling element remains inside of the unit and causes the coils to freeze. Not only does the air circulate slowly into the home due to the hindered fan, the blockage created by the ice prevents the fan from blowing the air through the cooling element. A number of things can cause the fan to malfunction, including debris, ball bearings in need of lubrication, and improperly mounted fan blades. After turning off the power, you can remove the fan-housing panels from the air conditioner unit to search the fan component for any problems.

Dirty Coil

The coils of the two-stage air conditioner should be cleaned approximately once a year to prevent dust buildup. If coils are left too dirty, the unit can freeze over and prevent air circulation through the unit and home. This leaves the current room temperature, which might be at 77 degrees Fahrenheit, unaltered. Panels on the outside of the air conditioner can be removed to more easily access the coils. The coils should be sprayed down thoroughly until it is free of all dirt buildup. Excess water should be drained or removed with a wet/dry vacuum.