How to decide whether to repair or replace your HVAC system. The $5,000 rule, age thresholds, refrigerant type, and efficiency math.
The industry rule of thumb: multiply the repair cost by the system's age in years. If the result exceeds $5,000, replacement is typically more economical. A 10-year-old system needing an $800 repair scores 8,000 — borderline. A 14-year-old system needing a $1,200 compressor repair scores 16,800 — replace.
This rule is a starting point, not a final answer. Three factors override it in either direction.
Systems using R-22 refrigerant (manufactured before 2010) face a structural cost problem. R-22 is phased out under EPA regulations and currently costs $50–$150 per pound to recharge, versus $3–$10 for the modern R-410A replacement. A system that needs a refrigerant recharge will need it again — the leak doesn't go away. R-22 systems almost always favor replacement.
Replacing a 10-SEER system with a 16-SEER system typically reduces cooling energy use by 37%. At average US electricity rates, that's $300–$600/year in savings depending on climate and usage. Over a 15-year system life, the efficiency gain often exceeds the replacement cost premium. The U.S. Department of Energy's Home Energy Saver tool can calculate site-specific savings estimates.
Central air conditioners last 15–20 years with proper maintenance. Heat pumps last 10–15 years. Gas furnaces last 20–30 years. If the system is within 3–5 years of end-of-life and the repair is significant, replacement avoids a second large expense in the near term. Use the estimator below to compare replacement cost against continued repair spending. See also: replacement cost ranges and what affects the final number.
Minor repairs on systems under 10 years old with a clean maintenance history almost always favor repair. A system replaced 7 years ago with a $400 capacitor failure has a clear answer. The decision framework above is for systems approaching end-of-life, facing major component failures, or using phased-out refrigerant.