Air Conditioning Service Guide
Start at the thermostat. Make sure that it is set to cool and that the thermostat setting is lower than the current room temperature.
If the thermostat is set properly and calling for air conditioning:
Go to the server of your floor, wall or ceiling supply registers. Is there air coming out of the register, and is it cold?
If there is no air coming out of the register:
Go outside to see if the fan on the outdoor unit is running. If the outdoor fan is not running, check the sure circuit breakers to ensure that they are not tripped.
If the breaker is tripped:
You can reset it by turning it off and then back on. If it trips again a service call is warranted.
If your unit has a condensate pump:
Check to make sure the reservoir is not full. If the reservoir is full, a limit switch will normally stop the air conditioner from running. You will need to repair or replace the pump.
If at this point the breaker and condensate pump are ok and nothing is operating:
Then the problem is probably the thermostat, the system control board (in the furnace or air handler, or the wiring between the indoor unit, the outdoor unit, and the thermostat.
If the indoor blower is operating but the outdoor fan is not:
Check to see if there is an outdoor disconnect, and that it is set properly.
If the indoor and outdoor fans are on:
Check the refrigerant lines at the indoor coil. Do you see heavy frost or ice on them? If there is frost, check the lines for proper air-flow. Is the system filter clean? Replace or clean it if necessary. Also, check that the return air grills are not obstructed and that the majority of supply registers are open.
If the refrigerant lines are not iced:
Check the outdoor unit coil. Is it relatively clean? Ensure that if is not obstructed by foreign material like leaves or pollen.
If the system seems to be operating, but outdoor conditions are extreme:
The unit may not be large enough to maintain a desired indoor conditions. During extreme conditions try to avoid activities that add to the thermal demands of your system including clothes drying, longer showers, oven use, or frequent opening of exterior doors.
If the unit operates and the airflow has been checked, but the cooling is inadequate or the refrigerant lines are iced a service call is warranted.