Standing over a broken AC with a repair quote in hand, you're really being asked a math question: does this repair buy enough life to beat putting the money toward a new system? Technicians have a shorthand for this — the $5,000 rule — and you can run it yourself in under a minute.
The $5,000 rule
Multiply the age of your system by the cost of the repair. Under $5,000: repair. Over $5,000: replacement usually wins. A $400 repair on a 6-year-old system scores 2,400 — easy repair. The same $400 repair on a 14-year-old system scores 5,600 — and that money is probably better spent on a system with 15 years ahead of it instead of one or two.
Run your numbers
What the rule doesn't capture
The $5,000 rule is a starting point, not a verdict. Tilt toward replacement when: this is the second major repair in two years; the system uses phased-out R-22 refrigerant (pre-2010 installs) or early R-410A equipment nearing end-of-support; your summer power bills have crept up year over year (efficiency loss is real and expensive at Florida runtimes); or the repair is a compressor or coil — the two components whose failure usually signals a system at end-of-life. See typical prices for both in our repair cost guide.
Tilt toward repair when: the system is under 10 years old; the fix is a wear part like a capacitor or contactor; or you need to buy a season while you plan a replacement on your terms — a scheduled install in October beats an emergency install during the first July heat wave, in both price and stress.
The efficiency math most people skip
A 12–15 year old system typically runs at 10–13 SEER effective efficiency; today's standard installs are 15.2 SEER2 and up. At Florida runtimes, that gap commonly means 20–35% off the cooling portion of your electric bill — often $40–$80/month in peak season for an average home. Replacement never feels cheap, but on an old, inefficient system, part of the payment is money you're currently donating to the power company.
Frequently asked questions
What is the $5,000 rule for AC replacement?
Multiply your system's age in years by the repair cost. If the result is under $5,000, repair is usually the smart money; over $5,000, replacement usually wins. A $600 repair on a 10-year-old unit scores exactly 6,000 — replacement territory.
How long do AC units last in Florida?
Typically 10–15 years — shorter than the national 15–20 because Florida systems run roughly double the annual hours. Past year 12, plan as if replacement could arrive any season, even if the system currently works.
Is it cheaper to replace an AC in the off-season?
Often, yes. Fall and winter installs mean better scheduling, more time to compare quotes, and occasional off-season equipment pricing. The most expensive replacement is the emergency one in July — which is exactly when systems choose to fail.
Should I replace my AC before it dies?
If it's 13+ years old, needs increasingly frequent repairs, or your bills keep climbing — proactive replacement lets you choose the timing, the equipment, and the price, instead of taking whatever is available during a heat wave. If it's younger and healthy, run it and maintain it.
Does a new AC increase home value?
In Florida, a new HVAC system is one of the first things buyers and inspectors check, and an aging one becomes a negotiating chip against you. You typically won't recoup the full cost at sale, but you avoid the discount an old system invites — and you get the efficiency savings while you live there.