You can determine the tonnage of all current Airease HVAC systems by finding the 7th and 8th Digits in the model number. 
An example would be: 4AC13L48P7A

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The Tonnage Chart is provided Below.

18 = 1.5 tons
24 = 2 tons
30 = 2.5 tons
36 = 3 tons
42 = 3.5 tons
48 = 4 tons
60 = 5 tons