Thanks in advance for those of you who act as my reference source. I beg another answer.
I inspected a house today with a Frigidaire air handler in the attic, Model B2BM018K-A, Serial #B2B9801-00968. I read the model # as 18,000 BTU. But the serial stumps me for the age. It is also paired with a 12 year old Trane condenser.
Thanks again for any guidance.