Why Is My Air Conditioner Not Cooling the House?

Thermostat Set Incorrectly

• The best-case scenario is that you simply have your thermostat set incorrectly on your air conditioning system. Switches and levers in the wring position are more common than you might imagine. Check to see that the system is turned on to begin with, and check the selector switch to see that the setting is on "cool" and not "heat." Also look at the temperature that the thermostat is set on and see if it is at a level that is actually lower than the room temperature. If it's 80 degrees in your house and you have the selector set to 82 degrees, the system already thinks it's cool enough and will not come on.

Circuit Breakers

• If the air conditioner is not blowing at all and nothing you do at the thermostat seems to be making a difference then you may not have power to the system. The first place to check is the circuit breaker box. Look at the legend and see which breaker controls the air conditioner. Make sure it is turned on and hasn't been tripped. If it has, you can usually turn it off and then back on to get power back to the system. If the air conditioner continues to trip breakers, you should call an HVAC specialist to see if there is a dangerous short or another problem with the air conditioner.

Filters

• If you haven't checked your air filter lately then you probably need a new one. The air filter is located at the air handler and there is generally easy access to it. The filters are made to last up to three months or longer depending on the specific type, but in reality these filters need to be changed monthly for the best cooling possible. If the filter becomes clogged with lint, hair, dust or other debris it can drastically affect the cooling capacity of the system by restricting the airflow.

Icy Coils and Low Refrigerant

• Low refrigerant may be the cause of your poor cooling. When the level gets low in your system it can actually make the temperature at the condenser coils get too cold. This will freeze the condensation that forms during normal operation. Over time, ice builds up on the coils, reduces airflow over the coils and results in only slightly cooled air or no cool air at all.