When it comes to home comfort systems, one of the most common questions homeowners ask is: “Do the furnace and air conditioner use the same filter?” The short answer is yes! In most modern HVAC systems, the furnace and AC share the same air filter.
Here’s why that matters, and what you need to know:
Why the Furnace and AC Share a Filter
Your furnace and air conditioner are actually part of the same system. Regardless of if you have central heating and cooling, separate units, or a heat pump, the system will use the same filter. Both the furnace and AC use the same ductwork to move air throughout your home. Because the air flows through the same pathway, the filter is placed in a central location, usually at the return air duct or inside the blower compartment, so that it protects both the heating and cooling components.
This means that whether your furnace is warming your home in the winter or your AC is cooling it in the summer, the same filter is doing the work of trapping dust, pet dander, pollen, and other airborne particles.
The Purpose of Your HVAC Filter
The filter isn’t just about keeping dust out of the air. It serves several important purposes:
- Protects the equipment: Dust and dirt can damage sensitive components like your blower motor, furnace heat exchanger, or AC coil. The filter prevents debris from building up inside your system.
- Improves efficiency: When the filter is clean, air flows freely. A clogged filter makes the system work harder, which increases energy bills and wears down equipment faster.
- Boosts indoor air quality: The filter traps allergens like pollen, pet dander, and dust mites, helping you breathe easier.
- Extends system lifespan: Preventing unnecessary strain means fewer breakdowns and a longer-lasting HVAC system.
Where Is the Filter Located?
In most systems, the filter is located:
- Inside or right next to the furnace cabinet (behind a small access door)
- In the return air vent (often a large grille on a wall, ceiling, or hallway)
If you’re not sure where yours is, check your system manual, or ask your HVAC technician to point it out during your next maintenance visit.
Are Filters Changed During Maintenance Visits?
Whether or not your furnace filter gets replaced during a maintenance visit can vary from company to company. Some HVAC providers build filter replacement directly into their maintenance plans and may even bring a filter along to your appointment, while others have shifted to recommending filter subscription or delivery services. These delivery programs ensure homeowners always have the correct size and type of filter on hand without the heating company needing to keep a wide variety of filters in stock.
In many cases, technicians will gladly install a new filter for you during a tune-up as long as you already have one available. At Quality Comfort Home Services, our team is happy to take care of this step for you; if you provide the replacement filter, we’ll make sure it’s swapped out during your visit so your system is running at its best! If you don’t have the filter on-hand, just let us know what size you need when booking your appointment and we can bring it with us to your tune up visit.
How Often Should You Change It?
Because the furnace and ac use the same filter, it’s working year-round. That means it can get dirty fast. As a rule of thumb:
- Standard filters: Replace every 1–3 months.
- Thicker, high-efficiency filters: Replace every 6–12 months, depending on your system and household needs.
- Homes with pets, allergies, or high dust levels: Change more often to maintain comfort and efficiency.
Read more about how often to change your filter and the types of filters here.
Signs It’s Time to Change Your Filter
- Rising energy bills without explanation
- Increased dust accumulations on surfaces
- Weak airflow coming from vents
- A visibly dirty or clogged filter
If you’re not sure where your filter is, what size you need, or how often it should be replaced, don’t stress. Quality Comfort has you covered. Our friendly HVAC experts can help you choose the right filter for your system, install it properly, and keep your furnace and AC running smoothly all year long.
