Your AC just quit, the house is warming up, and the tech at your condenser has two numbers for you: the repair, and — funny you should ask — a new system. He also has a commission structure you can't see. Repair-or-replace is genuinely a close call sometimes, but it's a math problem, not a judgment call, and you can run the math yourself in five questions.
Question 1: What does the $5,000 rule say?
The industry's cleanest rule of thumb: age of the system × cost of the repair. If the product is under $5,000, repair. Over, replace.
- 6-year-old unit, $400 fan motor → 2,400. Repair.
- 10-year-old unit, $650 leak repair and recharge → 6,500. Lean replace.
- 15-year-old unit, $2,200 compressor → 33,000. Replace, emphatically.
The rule works because it prices the real question — not "can this be fixed?" (almost anything can) but "how many years of remaining life am I buying with this repair?" A big repair on an old system buys very few, at a very high rate.
Question 2: What's actually broken?
Repairs aren't one category. A capacitor and a compressor are both "the AC broke," the way a flat tire and a thrown rod are both "car trouble."
| Repair | Typical cost | Verdict |
|---|---|---|
| Capacitor | $150–$400 | Fix it — routine wear item at any age |
| Contactor | $150–$400 | Fix it — same story |
| Condenser fan motor | $400–$700 | Fix it on systems under ~12 years |
| Blower motor | $500–$1,500 | Fix if young; think hard past 12 years |
| Refrigerant leak repair + recharge | $500–$1,500 and climbing on R-410A | Yellow flag — leaks recur, and old refrigerant gets pricier every year |
| Evaporator or condenser coil | $1,500–$2,500 | Replace the system unless it's young and under parts warranty |
| Compressor | $1,500–$3,000 | On a 10+ year system, this is a new-system down payment |
The pattern: small electrical parts are cheap, quick, and worth doing almost regardless of age. The big three — coils, compressors, and chronic refrigerant leaks — cost a third to half of a new system while fixing exactly one of the many old parts you'd still own afterward.
Question 3: How old is it — really?
Central ACs typically last 15–20 years, less in brutal climates or with skipped maintenance. The practical thresholds:
- Under 10 years: repair-first territory. The system likely has an active parts warranty and plenty of runway.
- 10–15 years: the judgment zone. Minor repairs, fine; anything over ~$1,000 deserves the $5,000-rule treatment and a real replacement quote for comparison.
- Over 15 years: every significant repair is a bet against the actuarial tables. Even repaired, the next failure is a matter of seasons, not years.
Not sure of the age? The manufacture date is encoded in the serial number on the outdoor unit's data plate — most brands print the week and year right in it, and a web search of the brand plus "serial number date" decodes it in a minute.
Question 4: What's the refrigerant situation?
This is the question that changed the math for 2026. If your system was installed between roughly 2010 and 2024, it runs on R-410A — and R-410A production is being phased down under federal law. Shrinking supply means the per-pound price rises every year, so a leak-and-recharge that cost a few hundred dollars a few summers ago can push toward four figures now, and will cost more next season than this one. You'd be paying a premium to top up a system that, by definition, leaks. Here's the full story on the refrigerant change and what it means for your wallet.
Question 5: What is the old unit costing you while it runs?
A failing system charges you even between repairs. Efficiency drifts down with age — worn compressors, dirty coils, and low charge can leave a 15-year-old unit performing far below its original rating, while a new mid-tier system cuts cooling energy by a quarter to a third against typical old equipment. Add the pattern most owners recognize — $300 here, $500 there, every summer — and "keeping the old one" has a real annual price even when nothing is currently broken. The honest comparison is that total against a new system's monthly payment, which for many homes runs $95–$150 — here's how the financing math works.
When repair is the right answer
Replacement isn't always the answer, and any company that says otherwise is selling, not advising. Repair with confidence when:
- The system is under ~10 years old and the compressor is healthy.
- The failed part is minor — capacitor, contactor, fan motor, thermostat.
- The parts warranty is active. Most manufacturers cover parts for 10 years when the unit was registered; you pay labor only. (Check whether the warranty transferred if you bought the house — some do, some lapsed at closing.)
- The failure has a clear cause — a chewed wire, a clogged drain line — rather than being the third mystery breakdown in two summers.
The decision, on one card
Run down this list and the answer usually falls out by step three:
- Age × repair cost over $5,000? Replace.
- Compressor or coil on a 10+ year system? Replace.
- R-410A leak on a 12+ year system? Replace — that repair only gets pricier.
- Minor part, healthy compressor, under 10 years? Repair and move on with your summer.
- Still genuinely torn? Get both numbers in writing — the repair quote you have, and a real all-in replacement price for your home — and run the rule with facts instead of a pitch. The second number takes about a minute at your address, and it turns a pressured driveway decision into arithmetic.