My central AC is a 16-year old Trane one package unit on the roof top. However, it is not cooling very well. I brought contractors in and it seems that R22 freon is leaking. However, every contractor gave me a different number of freon that I need to fill.
My question is 1) is it possible to test freon level for a one-package unit? If so, how? 2) do I need to replace it? Trane has solid quality and I thought it can last longer than 16 years. Replacement for a roof top central AC is so expansive since we will probably need a crane.
Many thanks in advance!