A new air conditioner typically lasts about 12 to 17 years, while a new furnace often lasts about 15 to 20 years with proper installation and maintenance.

What affects lifespan

  • Installation quality matters a lot, especially for both systems.
  • Regular maintenance can add years, while neglected filters and tune-ups can shorten the life of the equipment.
  • Usage level and climate also matter; heavier seasonal use usually means faster wear.

When to start planning replacement

  • If the AC is around 10 to 15 years old, it’s smart to start budgeting for a replacement soon.
  • If the furnace is nearing 15 to 20 years old, it may be entering the replacement window.
  • Frequent repairs, uneven heating or cooling, and rising energy bills are common signs the system is aging.

Practical rule

If the system is still working well and has been maintained, it can often run longer than the averages above. But once repairs start stacking up, replacement usually becomes the better long-term move.

TL;DR

Plan on about 12–17 years for AC and 15–20 years for a furnace , with maintenance and installation quality making the biggest difference.