Yes, You Can Replace Just the Furnace and Not the AC
A lot of homeowners are surprised to hear this, but you absolutely can replace just your furnace without replacing your air conditioner. The two systems might share some components — like the blower fan in the air handler — but they operate independently enough that you’re not forced into a full replacement if only one side of your HVAC system is on its last legs.
When It Makes Sense to Replace Just the Furnace
If your furnace is old, inefficient, or flat-out broken, but your AC is relatively new and working fine, replacing the furnace by itself can save you thousands. Furnaces typically last 15–20 years, while central AC units often need replacement closer to the 12–15 year mark. It’s very common for one to outlast the other by several years.
If your AC is running well and not using an outdated refrigerant (like R-22, which is already phased out), there’s no financial reason to toss it just because the furnace is ready for retirement.
The Shared Parts Question
Your furnace and AC do share the blower motor. That’s the big fan in the furnace that pushes warm air in the winter and cold air in the summer. If your old blower is failing, you’ll want to replace it with the furnace so your AC can still work properly. But that doesn’t mean you have to buy a whole new AC system.
Potential Downsides to a Furnace-Only Swap
…..Nothing really. Cutting the replacement job in half and spreading the trouble over 2-3 years can be a real game changer for a lot of homeowners. This changes if you are financing the replacement. Better terms are offered on larger tickets. If you’re paying out of pocket and the AC is still doing its job, just replace the furnace for now.
The Cost Advantage
The national average cost to replace a furnace runs between $3,000 and $6,000, while a combined furnace + AC replacement can easily hit $6,000–$12,000. If your AC is still in its prime, replacing just the furnace can keep a big chunk of change in your pocket.
Example math:
- New furnace only: $4,000
- Full furnace + AC replacement: $10,000
- Savings: $6,000
That’s enough to cover a vacation, some home upgrades, or even set aside for when the AC does eventually need to be replaced.
Bottom Line
If your AC is healthy, don’t let anyone pressure you into replacing it just because your furnace is done. A skilled HVAC contractor can install a new furnace and leave your AC ready to run for years to come. Just be sure the blower motor, coil, and ductwork are all in good condition, and you can save thousands without sacrificing comfort.