Many NAs still run original R-12 that may need R-134A conversion; a still-cold R-12 system is cited as proof of intact seals, compressor replacement runs roughly $900-$1,300 with parts sometimes scarce, and no A/C is a dealbreaker in southern heat.
Air conditioning: R-12 systems, conversion and compressor cost
Mazda MX-5 Miata (NA) · mechanical