First, at the thermostat, turn off your air conditioning system. When you've finished resetting it, you don't want it to start up your air conditioner for cooling right away. Look for the breaker box. Seek out a metal box or panel that is flush against a wall. Sometimes it is painted to match your home, but most of the time it is a simple metallic color. Then turn off the breaker for your air conditioner. Before turning the breaker back to the "on" position, wait at least one full minute. Before turning your unit back on at the thermostat, wait 30 minutes. This provides an opportunity for your system to reset its internal circuit breaker.