A simple rule many technicians use: multiply your AC’s age in years by the repair cost. If the result is more than 5,000, replacement usually makes more sense; if it’s less, repair. A second check: if a repair costs more than about half the price of a new system, replace. Age, refrigerant type, repair history and your energy bills all fine-tune the decision.
Quick answers
- Age × repair cost > 5,000 → lean toward replacing.
- Repair over ~50% of replacement cost → replace.
- Under 10 years old: repair in most cases.
- Over 15 years old with a compressor or coil failure: replace in most cases.
- Always get a written diagnosis with the failed part named.
The 5,000 rule in action
| AC age | Repair cost | Age × cost | Lean toward |
|---|---|---|---|
| 6 years | 450 USD | 2,700 | Repair |
| 9 years | 1,200 USD | 10,800 | Replace (unless under warranty) |
| 12 years | 350 USD | 4,200 | Repair, but start planning |
| 14 years | 600 USD | 8,400 | Replace |
| 16 years | 250 USD | 4,000 | Repair if minor, plan replacement |
Some contractors adjust the threshold upward over time because repair and equipment prices have risen. Use it as a guide, not a law.
Repairs that usually make sense
- Capacitors and contactors
- Fan motors on systems under about 12 years
- Thermostat replacement
- Drain line clearing and float switch repair
- Small refrigerant leak at a fitting or valve on a newer system
- Control boards on systems under warranty
Situations that usually favor replacement
- Compressor failure outside the warranty on a system over about 10 years old
- Leaking coil on an older R-410A system (refrigerant is getting more expensive: R-410A Phase-Out)
- Repeated repairs two seasons in a row
- System over 15 years old with any major repair
- Very high bills and poor comfort even after maintenance
- Wrong size: the system never kept up or always short-cycled
Check your warranty first
Many manufacturers offer 10-year parts warranties if the system was registered after installation. A compressor under warranty may only cost labor and refrigerant. Find the serial number on the outdoor unit and check the manufacturer’s warranty lookup.
Questions to ask the technician
- Which part failed, and how did you confirm it?
- Is the part under warranty?
- What’s the total price, including refrigerant and labor?
- What other components are close to failure?
- If I replace, what size and efficiency do you recommend, and why?
Avoid being pressured
Get a second opinion for any recommendation to replace a system under 10 years old or any single repair over 1,500 USD. Be wary of claims that you must replace an R-410A system immediately because of the phase-out.
Costs to compare
- Common repairs: AC Blowing Warm Air? 11 Causes and How to Fix Each One
- Replacement: AC Replacement Cost in 2026
- Lifespan: How Long Do AC Units Last?
Frequently asked questions
Is it worth repairing a 20-year-old AC?
Only for a very small repair while you plan a replacement. It likely uses R-22 or early R-410A and is far less efficient than modern systems.
Should I replace my furnace at the same time?
If the furnace is over 15 years old, replacing both together saves on labor and ensures matched equipment. Consider a heat pump or dual-fuel system.
Can I just add refrigerant every year?
That means you have a leak. Repeated recharging is costly and harmful to the environment; fix the leak or replace.