Your system broke down, a tech gave you a repair price, and now you’re wondering if you should just replace the whole thing. We get this call a lot. There’s no single right answer, but there are a few questions that sort most situations out pretty fast.
Start with age
Age isn’t everything, but it tells you a lot. Central air conditioners commonly last somewhere around 15 to 20 years, and gas furnaces land in a similar range with good maintenance. Some go longer. Some die well before that, especially when they were installed poorly or never serviced.
A $300 repair on a 6-year-old system is an easy yes. The same $300 on a 19-year-old system is a harder call, because it’s probably not the last repair.
The “$5,000 rule”
A rule of thumb you’ll hear from contractors goes like this. Multiply the age of the equipment by the repair cost.
- If the result is over $5,000, replacement is usually worth a serious look.
- If it’s under $5,000, repair usually makes more sense.
A 12-year-old AC with a $500 repair comes out to $6,000. Time to at least price a replacement. A 7-year-old unit with a $400 repair comes out to $2,800. Fix it.
It’s a quick filter, not a verdict. A few things it doesn’t account for:
- What’s being repaired. A capacitor or contactor is a routine part. A compressor or a leaking coil on an old system is a different conversation.
- Repair history. Three service calls in two summers adds up, even if each one was small.
- The refrigerant it uses. More on that below.
- Efficiency. An older, lower-efficiency system costs more to run every month.
If your system uses R-22, plan for replacement
R-22 (sometimes called Freon) was the standard refrigerant for decades. New equipment stopped being charged with it in 2010, and U.S. production and import of R-22 ended on January 1, 2020. What’s left for servicing comes from stockpiles and reclaimed refrigerant.
That doesn’t mean you have to rip out a working R-22 system. If it’s running fine, run it. But if it has a refrigerant leak, the repair gets expensive fast, and you’re putting money into equipment that’s at least 15 years old by now. In most cases, that’s the point to replace.
Today’s R-410A systems are on their way out too. New residential equipment has moved to A2L refrigerants like R-32 and R-454B. Our refrigerant guide explains what that means if you’re repairing an R-410A system versus replacing it.
Efficiency and comfort
A system from the early 2000s was likely built to a much lower efficiency minimum than today’s. The current federal minimum for a new split AC is 13.4 SEER2 in the North and 14.3 SEER2 in the Southeast and Southwest (for units under 45,000 BTU). New split heat pumps must be at least 14.3 SEER2 nationwide.
We won’t tell you a new system will pay for itself, because that depends on your rates, your climate and how you use it. You can plug your own numbers into our SEER savings calculator and see.
Comfort counts too. If some rooms never cool off, the house feels sticky in summer, or the system runs constantly, a repair won’t fix that. Sometimes the issue is sizing or ductwork, and replacement is the time to address it.
A cracked heat exchanger is a safety issue
This is the one situation where we don’t think there’s much to weigh. The heat exchanger keeps combustion gases, including carbon monoxide, separate from the air that blows through your house. If it cracks, those gases can get into the airstream.
Techs and gas utility inspectors will often “red tag” a furnace with a cracked heat exchanger, which means it’s shut off and marked unsafe to use until it’s fixed and reinspected. On most residential furnaces, replacing the heat exchanger is a big, labor-heavy job, and on an older furnace, replacing the furnace is usually the better spend. Check whether the heat exchanger is still under warranty before you decide.
Whatever you do, don’t run a red-tagged furnace. And if you don’t already have carbon monoxide detectors, get them.
When to replace both halves
A split system has two halves: the outdoor unit (AC or heat pump) and the indoor side (furnace with a coil, or an air handler). When one fails, it’s tempting to replace just that piece. Sometimes that’s the right move. Often it isn’t.
Replace both when:
- The outdoor unit is failing and the system is R-22 or R-410A. New outdoor units use A2L refrigerants and need an indoor coil listed for that refrigerant. You can’t pair a new R-32 condenser with your old R-410A coil.
- Both halves are about the same age and both are old. If the furnace is 17 years old and the AC dies, the furnace isn’t far behind. Doing them together usually costs less in labor than two separate jobs, and you get matched equipment.
- The furnace is failing and the new one is a different width. The coil sits on the furnace. If it won’t fit, it’s getting replaced or adapted anyway.
Replacing just one half can make sense when the other half is fairly new, in good shape, and compatible. A five-year-old furnace with a coil that’s already rated for the new refrigerant can stay put while you replace the outdoor unit. Your installer can tell you.
A matched system also matters for warranty and for the efficiency rating. The SEER2 on a system is rated for specific combinations of outdoor unit and indoor coil or air handler. Mix-and-match parts may not hit that number.
A quick checklist
Lean toward repair if:
- The system is under about 10 years old
- Age times repair cost comes out well under $5,000
- It’s a routine part and the system has been reliable
- It cools and heats the house evenly
Lean toward replacement if:
- It’s 15 years old or more and needs a major repair
- It uses R-22 and has a leak
- The furnace has a cracked heat exchanger
- It’s needed several repairs in the last couple of years
- The house is uncomfortable even when it’s working
If you land on replace, our system replacement cost guide covers what to expect, and the system selector will help you find a matched system.
Common questions
What is the $5,000 rule for HVAC?
Multiply the system’s age in years by the repair cost. If the result is over $5,000, replacement is usually worth considering. Under $5,000, repair usually makes more sense. It’s a starting point, not a substitute for a contractor looking at the system.
Should I repair an R-22 system?
If it’s a small repair and the system is running fine, it can be worth it. If it has a refrigerant leak, R-22 is only available from stockpiled and reclaimed supply, so the repair can get expensive. Most R-22 systems with leaks are better off replaced.
Is a cracked heat exchanger dangerous?
Yes. A crack can let combustion gases, including carbon monoxide, into the air in your home. A furnace with a cracked heat exchanger is often red-tagged and should not be used until it’s repaired or replaced.
Can I replace just my AC and keep my old coil?
Usually not anymore. New AC and heat pump systems use A2L refrigerants and need an indoor coil listed for that refrigerant. Plan on replacing the coil with the outdoor unit.
Not sure which way to go? Call us at (877) 843-4822 with your model numbers, or send us a message.