If you've turned on your air conditioner but aren't getting any cold air, your thermostat may need to be adjusted. If the thermostat on your air conditioner isn't working correctly, it won't be able to detect the temperature, and no matter how hard you crank the knobs, you'll never be cool.   Thermostats are built to be long-lasting and dependable, but that does not mean they will never fail. If you suspect a problem with your air conditioner, the first thing you should do is reset the thermostat. Here are the steps to reset your air conditioning thermostat.   Turn Off Your Air Conditioner at the Thermostat: Turning off the AC unit is the first step in resetting your AC thermostat. Make sure the air conditioning unit's shutdown is turned off and the thermostat is set to "off."   Locate the Circuit Breaker Box: Locate your circuit breaker as well as the air conditioning unit's control. Your circuit breaker box might be in your basement if you have one. Otherwise, go through your closets and crawl areas for the breaker box.   Restart your air conditioner by resetting the circuit breaker: The objects that each circuit regulates should be labeled on your circuit breaker box, so search carefully until you discover your air conditioner. Make that the circuit breaker for the air conditioner is in the "off" position.   30-second pause: It's critical to wait 30 seconds before resetting the circuit breaker. Return the AC circuit breaker to the "on" position after half a minute.   Restart the air conditioner: It's time to put your air conditioner's thermostat to the test now that you've reset it. Check to see whether the thermostat is still set to "off," then slowly turn it back on. Restart your air conditioner, adjust the setting, and wait for the cold air to come back.