How do you tell the tonnage off of a trane air conditioner name plate?

Should be the last 2 numbers in the model number followed by letters. Here's what to look for...

18=1.5 ton

24=2 ton

30=2.5 ton

36=3 ton

42=3.5 ton

48=4 ton

54=4.5 ton

60=5 ton

Every 12,000 BTU equal 1 ton.

Hope this helps.