Few things are worse on a hot summer day than finding that your air conditioner won't turn on. While major problems require professional fixes and expensive replacements, some problems are easy to detect and fix, even without handyman experience. Finding your central air's problem also gives you a chance to learn your way around the machine.
Make sure the air conditioner is set to a temperature below the current room temperature. This is the key to an air conditioner turning on.
Check power outlets to make sure they aren't the culprits. Plug in another device--such as a lamp--to see if it works in the same outlet. If the power is out, move on to circuit breakers and fuses. If they're not working either, you'll need an electrician, according to the Repair Clinic website.
Check the wiring. Burnt wires may prevent electricity from running the air conditioner. If wires are in the garage or outside, an animal may have chewed through the wires.
Make sure the thermostat is on "cool" and is working. To check this, turn the air conditioner off, remove the thermostat's cover and unscrew the Y terminal wire. Turn on the power. Hold the wire by the outer covering--without touching the bare wire--and hold the bare wire against the R terminal for two minutes. According to home improvement author Don Vandervort, if the compressor starts working, it means the thermostat is broken. A faulty thermostat sends bad signals to the air conditioner and may trick it into thinking it is colder than it is, and therefore it doesn't need to turn on.
Visit the outdoor air conditioner unit and look at the condenser power switch. Make sure it is turned on.
Call a repair worker if none of these problems fits. Many problems--such as problems with the compressor--require the help of a professional technician, according to Repair Clinic website.