Quick answer
AC compressor repair starts with testing the parts that keep a compressor from starting: the run capacitor, the contactor, the wiring and the internal overload. Many Miami compressor calls are solved with those parts or a hard-start kit. If the windings are shorted or the compressor is locked, the choice is a compressor replacement or a new system, and we show both prices.
Written by Sylvia Denton, HVAC Guides Editor. Updated 2026-09-22.
The compressor is the most expensive single part in an air conditioner, which is why the word makes homeowners nervous. The good news is that a compressor that will not run is very often healthy and simply is not being started. A weak dual run capacitor, a pitted contactor or a loose wire will leave a perfectly good compressor humming against the load until its overload trips.
We test in order of cost. Capacitor microfarads, contactor voltage drop, supply voltage under load, and the resistance of the start, run and common windings tell us whether the compressor itself is at fault. Amp draw once it starts shows whether it is pulling what the nameplate allows or dragging itself to an early failure.
When the compressor really is finished, the decision depends on the age of the system. On a five-year-old unit still under the manufacturer's compressor warranty, replacement is usually the right move. On a fourteen-year-old system with an old coil, putting a new compressor into it rarely makes sense, and we will say so.
