There are some things you can troubleshoot before you call in the experts. First, check your electrical box. See if the breaker for your heating & cooling (HVAC) system has been tripped or a fuse blown. Next, check your thermostat. Make sure it is set on “Cool” with the fan switch set to “Auto” or “On”. Also, check your thermostat by setting the temperature 10 degrees below room temperature to make sure your system turns on. Last, be sure that the air filter has been changed prior to turning on the air conditioner and that all air vents are open and clear from obstruction. If none of these steps are able to fix your problem, you should call a professional air conditioning technician to access and fix the problem.