How Long Does a Central AC Last — and What Shortens That Window

Most central air conditioners last 15 to 20 years. That’s the honest answer. Some push past 20 with good maintenance and mild Bay Area winters; others are done at 12 because they ran hard, got neglected, or were undersized from the start. If you’re staring at a repair quote on a unit that’s 14 or 15 years old, that age range matters.

What the Lifespan Looks Like by Brand

The big names hold up differently, and it’s worth knowing roughly where they land. These are generalizations, not guarantees.

Carrier and Trane both carry a reputation for running 18 to 20 years with proper maintenance. They’re not identical, but they’re in the same tier. Parts availability stays reasonable through most of that window.

Goodman tends to run closer to 15 to 18 years. They’re a value brand and there’s nothing wrong with them, but they’re built to a price point. You’ll see more compressor issues after year 12 or 13 if the unit has been pushed hard.

Lennox is in the Carrier/Trane range for lifespan, though it tends to show sensitivity to maintenance gaps. Dirty coils or chronically low refrigerant seem to hit Lennox systems harder than some other brands, so staying on top of tune-ups matters more.

Keep in mind: industry technicians consistently note that installation quality matters as much as brand. A Goodman that’s been serviced every year and runs in a mild coastal microclimate can outlast a neglected Carrier in a hot inland suburb.

What Actually Shortens That Window

A few things cut years off faster than age alone.

Skipped maintenance. Dirty coils make the compressor work harder. The compressor is the most expensive component in the system; replacing one typically runs $1,500 to $2,800 installed, sometimes more depending on system size and refrigerant type. Running it hard year after year wears it down. Annual or biannual tune-ups, including coil cleaning and refrigerant checks, are the single biggest thing you can do to get full life out of the unit.

Low refrigerant. If the system has been slowly leaking and nobody caught it, the compressor runs hot and struggles. What refrigerant your unit uses matters here, too. Systems installed before 2010 are likely on R-22, which was banned from new equipment in 2010 and is now only available as reclaimed supply at prices that can run $100 or more per pound. A unit still on R-22 that needs a refrigerant charge is worth a harder conversation about replacement. Systems installed from 2010 onward use R-410A, which is also being phased down under federal rules starting in 2025, so that refrigerant is becoming more expensive as well.

Oversized or undersized equipment. A unit that’s too big short-cycles (turns on and off too frequently), which beats up the compressor and leaves the house humid. One that’s too small runs constantly. Either way, you’re putting more hours on the equipment per year than a properly sized system would accumulate.

Coastal salt air. This is specific to Bay Area homes near the water. Salt corrodes the outdoor condenser coils faster than inland installations. If you’re in Pacifica, Half Moon Bay, or anywhere close to the Bay shore, expect to see coil degradation earlier and plan for it.

Poor installation originally. This one’s invisible until something fails. Undersized ductwork, bad refrigerant charge on day one, improper electrical connections. These don’t show up immediately but they grind components down over years.

How a Tech Diagnoses Where a Unit Stands

When we look at a system to answer the “repair or replace” question, here’s what we’re checking.

Refrigerant pressure tells us if the system is holding charge or leaking. Compressor amperage draw tells us how hard it’s working relative to specs. We’ll look at the condenser coil condition and check for corrosion. We check the capacitors (cheap, common failure) and contactors. On older units we check refrigerant type, because R-22 availability changes the math on repairs significantly.

If the compressor is pulling high amps and the coils are corroded and it’s on R-22 (meaning it was installed before 2010), that’s a different picture than a 15-year-old Trane that just needs a capacitor and a coil cleaning.

The Repair-or-Replace Calculation

A rough rule that holds up in practice: if the repair cost is more than half the cost of a new system, and the unit is past the 12-to-15-year mark, replacement usually makes more financial sense. Not always, but usually.

New systems are significantly more efficient. A unit installed in 2008 or 2010 is probably running at around 13 SEER, which was the federal minimum for that era. California’s current minimum for new equipment is 14.3 SEER2 (roughly equivalent to the old 15 SEER under updated test standards), and most mid-range systems land in the 16 to 18 SEER range. That efficiency gap shows up in electricity bills every month.

There are also rebates available in California for high-efficiency systems and heat pump conversions. PG&E territory, for example, has had rebates up to $2,500 for qualifying heat pump HVAC systems, and income-qualified programs go higher. Other Bay Area municipal utilities have their own programs. It’s worth checking what’s current before you commit to a major repair on an old unit, because the numbers can change the replacement calculation significantly.

What You Can Check Yourself

A few things are safe for a homeowner to look at before calling anyone.

Check and replace the air filter if it’s clogged. A dirty filter restricts airflow enough to cause the system to freeze up or short-cycle. This is the number one DIY fix.

Clear the area around the outdoor condenser. Vegetation, debris, and fencing that restrict airflow around the unit hurt performance and longevity. Keep at least two feet of clearance on all sides.

Check that the condensate drain line isn’t backed up. A clogged drain causes the pan to overflow and will trigger a shutoff on many systems. Flushing it with water or a wet-dry vac is a reasonable DIY step.

Beyond that, leave it to someone with the right tools. Refrigerant handling requires EPA certification under Section 608 of the Clean Air Act. Electrical work on the unit carries real shock risk. Compressor diagnosis requires gauges and amperage readings that most homeowners don’t have.

When to Call a Pro

If the unit is over 10 years old and something significant fails (compressor, condenser coil, control board), get a professional opinion on whether repair or replacement makes sense before authorizing the work. A good tech should be willing to walk you through the numbers honestly.

If you’re in the Bay Area and want a straight answer on where your system stands, the team at bayareahvacservice.com does diagnostic calls and can give you a real repair-versus-replace assessment without pressure to go either direction.

Key takeaways

• Most central AC units last 15 to 20 years; brand, maintenance history, and local conditions all shift that range.
• Skipped tune-ups and low refrigerant are the two biggest factors that shorten compressor life early.
• If a repair quote exceeds roughly half the cost of a new system and the unit is past 12 to 15 years old, replacement usually wins financially.
• Bay Area coastal homes see faster coil corrosion from salt air, which is worth factoring into your timeline.
• California rebates on high-efficiency and heat pump systems can change the replacement math significantly — PG&E territory has had rebates up to $2,500 for qualifying systems; check current availability before committing to a major repair.

Related questions

Written by Andrew Kuznetsov. Andrew is the founder and owner of Bay Area HVAC Service (ADRIUM Service Solutions). He holds a California Contractor License (CSLB #1136642), EPA 608 certification, and completed factory training at the Daikin/Goodman plant in Houston in 2025. He writes from direct field experience, not marketing copy.

Further reading

• Mitsubishi Hyper-Heat (H2i): How It Keeps Putting Out Heat When It Gets Cold in the Bay Area , Most people think heat pumps quit when it gets cold. Mitsubishi's Hyper-Heat (H2i) line is built to keep working as temperatures drop, which matters more here than folks expect, especially on cold mornings and up in the East Bay hills.
• Mitsubishi Mini-Split Blinking a Fault Light? What It Means and What to Do , A blinking light on your Mitsubishi indoor head is the system telling you something is wrong. Here is what the blink pattern means, the checks you can safely do yourself, and when to bring in a factory-trained tech.
• Why Your Mitsubishi Mini-Split Is Leaking Water Inside (and How to Fix It) , A Mitsubishi mini-split dripping water inside almost always comes down to condensate that can't drain. Here's what causes it, the safe checks you can do yourself, and when to call a tech.