Hi All - Just looking for some general guidance. Thanks in advance.

I live in a 2150 sq. ft. 2-story home in the inland part of the SF Bay area (built in 1998). It gets quite warm in the summer (80's-90's) and we use the A/C a lot but hardly use the heater in the winter. I am looking to replace/upgrade the current outdoor A/C unit which is in very bad condition. My whole system is comprised of: York Diamond 80 furnace (P3HUA12L04801B), outdoor York condenser (H2RA036S06A), and an unknown indoor coil unit that sits next to the furnace (can't find any labels on it - looks very generic).

From what I have read, it sounds like my system is undersized for the size of home and that I should upgrade to a 4 ton condenser with matching indoor coil. And although there does not appear to be anything wrong with the furnace portion of my system, I am thinking that it might be undersized for a 4 ton condenser. Wondering if this is the case and, if so, what might be an appropriate size for the furnace. I have scheduled several visits for quotes next week - just want to be as informed as I can prior to the visits.

Thank you!