"Check to see if there is power getting to the air conditioning system. If it is a 110-volt unit, then plug a lamp or other device into the same outlet the air conditioner is plugged into. If there's no power, check the fuses or circuit breakers. If there's still no power, you will need to contact a qualified electrician to restore power to the outlet. If there is power to the appliance but it is still completely dead there may be a problem in the following areas: Wiring (Inspect for any broken or burnt wiring) Thermostat Compressor Overload and/or relay Selector switch Control board Work on these areas of an appliance may require help from an appliance repair person or other qualified technician."