Steve at HvacPartsShop.com explains the useful information on the service tag of your air-conditioning unit. The model and serial number as well as motor, compressor and charge are covered in the explanation. The correct model and serial number are of critical importance in your receiving the manufacturer recommended replacement motor, compressor, condenser coil, crankcase heater, contactor, high side limit, low side limit , fan, defrost control or capacitor for your air-conditioner.