Why it matters to you
A Houston AC with the wrong refrigerant charge works harder through a long cooling season and can remove less humidity. Measuring superheat or subcooling against the manufacturer's chart is how a technician confirms the charge instead of guessing from pressure alone.
Practical guidance
After a tune-up or refrigerant repair, ask which reading the technician checked — subcooling is typically used on systems with a TXV, superheat on fixed-orifice systems — and whether it matched the manufacturer's target. Taking these readings means connecting gauges to the refrigerant circuit, which is certified-technician work.