Locate the unit's serial plate. This can be found on the top or the right or left side of the air conditioner. Sometimes, the serial plate can be located behind the front grill.
Write down the serial number and the model number. The model number will be printed near the words "Model No." and usually starts with letters. The serial number will be printed near the words Serial No." and usually starts with numbers.
Keep the model number and serial number in a safe and convenient location for future reference.