Quick answer
An AC replacement in Miami swaps the outdoor condenser and indoor air handler as a matched system, usually with a new line set, drain pan and float switch, under a Miami-Dade permit and inspection. Replacement typically makes sense when a system is over 12 to 15 years old, needs a major repair such as a compressor or coil, or still runs on R-22 refrigerant.
Written by Sylvia Denton, HVAC Guides Editor. Updated 2026-09-22.
Most replacement calls start as repair calls. The compressor has failed, the coil is leaking again, or the unit simply cannot keep the house below 80 degrees in August. At that point the question is whether to put more money into the old system or put it toward a new one.
We use a simple rule of thumb and then check it against your situation: multiply the age of the system by the repair cost. If the result is more than about $5,000, replacement usually wins. A 14-year-old system facing a $1,800 coil replacement scores over $25,000, which is a clear signal. A 6-year-old system with a $400 motor repair is not close.
Other factors move the line. Systems still on R-22 refrigerant are expensive to recharge because that refrigerant is no longer produced. Units with rusted cabinets and failing coils from salt air rarely justify a big repair. And a new system at 16 or 17 SEER2 can cut the cooling part of a Miami electric bill by a third or more compared with a tired 10 SEER unit.
