The short answer
Repair is usually sensible for a younger system with one failed part. Replacement deserves a hard look when the system is near the end of its typical life, repairs keep coming, it uses R-22, or there is a safety problem such as a cracked heat exchanger. Get the diagnosis and both prices in writing, and a second opinion unless it is an emergency.
How old is the system?
Typical service lives vary widely with climate, use and maintenance. As a rough guide, central air conditioners and heat pumps often last 12 to 17 years, and gas furnaces often 15 to 20 years or more. The age is usually on the unit’s label as a manufacture date or within the serial number – ask the technician to show you.
Repair history and the size of the repair
One failed capacitor, igniter or motor on a sound system is a repair. A failing compressor, a leaking coil, or a run of repairs in recent years on an older system is where replacement starts to make sense. Some people use a rough rule of thumb – multiply the age by the repair cost, and if the result is above about $5,000, price a replacement. Treat it as a prompt to compare, not an answer.
Safety problems change the answer
A cracked heat exchanger in a furnace can leak carbon monoxide. If a technician reports one, ask to see the evidence (a photo or camera inspection) and, if the furnace is not under warranty, a second opinion. Do not run a furnace that has been shut off for a safety reason.
Refrigerant type
An R-22 system with a leak is a strong candidate for replacement because R-22 is no longer produced. R-410A systems can still be repaired. See refrigerant changes.
Efficiency and comfort
A new system can use noticeably less energy than one from the early 2000s, and variable-speed equipment can fix hot and cold rooms and humidity problems. But savings depend on use and energy prices, and comfort problems are often ductwork, not equipment. Ask for a load calculation and a duct check before replacing for comfort.
Replacing one half of a split system
Replacing only the outdoor unit and keeping an old indoor coil can reduce efficiency, void warranties, or not be possible with newer refrigerants. Ask whether the quote is a matched system and for its AHRI reference number.
Questions to ask the technician
- What exactly failed, and can you show me?
- What does the repair cost, and what is its warranty?
- Is the equipment still under manufacturer warranty?
- What else is wearing out, and how soon?
- If I replace, what size and why – was a load calculation done?
- What is included: permit, removal, thermostat, ductwork, electrical?
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Questions
How long does an HVAC system last?
It varies with climate, use and care. Air conditioners and heat pumps often last 12 to 17 years; gas furnaces often 15 to 20 years or more.
Is it worth repairing a 15-year-old AC?
It depends on the repair, the refrigerant and the system’s condition. A small repair on a sound R-410A system can be worthwhile; a compressor failure or a leak on an R-22 system usually tips toward replacement.
Should I get a second opinion before replacing my HVAC?
Yes, unless it is an emergency. Replacement is a large purchase, and a second written quote often clarifies both the diagnosis and the price.
Related guides
Updated October 2026 by the Heating and Cooling editorial team. General information for homeowners, not professional advice – rules and equipment differ. When gas, carbon monoxide, electricity or anyone’s safety is involved, call 911 or your utility. How we write our guides · HVAC glossary