Your home's central air conditioner unit may tell you that it needs repair simply by no longer working, but signs of needed work are not always this obvious. You might also be able to make some simple repairs yourself if you understand common problems for an air conditioner to stop working as it should. In other cases, you may want to know what to say to a repair person about what you've managed to troubleshoot on your own. Note a few suggestions.
1. When the fan won't come on.
If you hear the unit humming but don't feel any cool air in the home because the fan is not working, your unit may simply need a new fan altogether. However, you can also test the unit by putting a long screwdriver into the top of the unit, being careful not to touch anything but the fan blades, and giving them a spin in a counterclockwise direction. If the fan then starts to work, your air conditioner needs what is called a capacitor. This is a part that uses electricity to actually start the motor of the fan. The motor may be functioning, but if the capacitor is broken, the motor simply won't start, like having a dead battery in your car.
2. When nothing runs.
One thing that many homeowners overlook when it comes to their central air conditioner is the drain pipe that is located outside the unit. Air conditioners remove moisture from the air, and this moisture is drained out a tube or pipe next to the unit. If the pipe is blocked, either by a foreign object or because of the buildup of algae, the unit simply won't come on. A crimped pipe or tube may also block the water drainage, and in turn, your unit won't operate.
3. Your home just doesn't seem cool enough.
Does the home seem cool in one part but warm in another? Your unit may be undersized for your home and simply cannot create enough cool air for the space. If the air seems warm and also dusty, your home's ductwork may need cleaning. Dust and debris can get in the way of cool air.
In some cases, the unit may need a recharge of refrigerant or the thermostat wiring may be damaged. Note if the unit comes on when you switch the fan to auto, and if so, this usually means the unit isn't reading the home's temperature as it should and the wiring is probably damaged.