Troubleshooting Your Air Conditioner
Start by checking the condition of the thermostat. If the thermostat is working properly, the air conditioner should automatically kick in as soon as the temperature in the room rises above the thermostat setting. Start your troubleshooting by making sure the thermostat is set to cool and that the temperature in the room is higher than the setting on the thermostat. It is important not to guess about the temperature---use a thermometer placed right next to the air conditioner to be sure.
Place your ear next to the air conditioner and listen for the fan. If you do not hear the fan running on the inside of the house, go outside and listen for the fan on the outside. If the fan does not appear to be running the next step is to check the power. It is possible that a fuse has blown or a circuit breaker has been tripped. Unplug the air conditioner and plug in another appliance in its place. If there is no power, check the electrical circuit board for a blown fuse or a bad circuit. If there is electricity flowing, continue your troubleshooting.
Check the condition of the air conditioner filter. Changing the filter should be part of your regular maintenance, so if it has been a while since the filters were changed, they could be blocked or dirty. If the weather has been particularly hot and dusty your filters may need to be changed more often, and if they are blocked it could cause the air conditioner to run poorly or not run at all.
Empty the reservoir in the air conditioner. If your air conditioner uses a condensate pump, the unit may shut off when the reservoir becomes full. Be sure to check the reservoir and empty it if necessary.