The model number is typically found on the data plate that is located on the side of the AC compressor, according to Comprehensive Building Consultants. The exact location can vary slightly based on the model of the particular AC compressor in question.
The compressor is the outside portion of the AC system. The data plate on the compressor can also tell the operator the serial number, manufacturer number and date on which the unit was manufactured. The data plate also usually contains information essential to the safe operation of the device, such as how many amps the unit is able to handle.