Should I repair or replace my AC?

The rule of thumb that holds up in Houston: under ten years old, repair it. Over fifteen, replace it unless the repair is trivial. Between ten and fifteen, which is where most of the hard calls sit, it turns on what failed and what the system runs on.

If the failed part is a compressor or an evaporator coil, those are the two most expensive parts in the system and the two that signal the rest is tired. If the system uses a refrigerant that is being phased out, the gas alone makes any sealed-system repair expensive and the next leak will cost the same again. And if this is the second major repair in two summers, the third is coming.

Two things that tip it towards replacement that people forget: a modern system on a Houston cooling load can cut the electricity bill noticeably, and a replacement done in October or February is done on the contractor's schedule rather than yours. The thing that tips it towards repair: a system that has been maintained, that uses current refrigerant, and that has failed on a small part.