What a clogged furnace filter looks like
This return air filter came out at the start of one of our visits, grey and loaded with dust. A filter this full chokes the air the system can pull in, so it works harder and the rooms take longer to warm up.
5.0 stars across 1,130 reviews
Get your price in writing
Send this and the office calls or texts you back to set a time.
We’ll call or text this number about your request. By sending it you agree to our terms and privacy policy.
Rather talk now? (703) 997-9757
Licensed and insuredVirginia Class A contractor #2705192276
24/7 emergency serviceWe answer day or night, and we will tell you honestly when we can get there.
Our own HVAC installersA dedicated heating and cooling team, separate from our plumbers
Price in writing firstYou see every option priced before anything is ordered
From one of our jobs
A return air filter well past its change
Right now: Slide the filter out and hold it up to a light. If you can’t see through it, put in a new one now.
The filter’s job is to catch dust before it reaches the blower and the coil. Once it’s packed like this, air goes around it or barely through it, and what slips past ends up on the blower wheel and in your ducts.
Every Heating Check starts with the filter. We tell you the size, how often yours needs changing and what we saw further in.
Quick answers
What people ask about clogged furnace filters
What does a clogged furnace filter look like?
Grey or black, with dust packed into the pleats so you can’t see light through it. A new one is white or light colored.
What happens if you don’t change your furnace filter?
Airflow drops, the furnace runs longer and can overheat and shut itself off, and dust that slips past coats the blower wheel and the coil.
How often should I change my furnace filter?
One inch filters about every one to three months. Thicker media filters every six to twelve. Pets and construction dust mean sooner.
Can a dirty filter stop the furnace from working?
Yes. A packed filter can make the furnace overheat and shut down on its safety switch, then start again, over and over.
Who checks furnaces in Northern Virginia?
Call SwiftPro at (703) 997-9757. Every Heating Check starts with the filter.
Seeing this at your house?
Tell us what you’re seeing. We’ll tell you what it is and what the fix costs, in writing.
What it costs
What we charge to check your furnace
Read and watch next
More on this from SwiftPro
More real photos from our jobs
Seeing this at your house?
Want us to take a look at yours?
Tell us what you’re seeing. We’ll give you a time and a price in writing before any work starts.
SwiftPro Heating, Cooling & Plumbing
4230 Lafayette Center Dr N, Chantilly, VA 20151
44679 Endicott Dr, Suite 211, Ashburn, VA 20147
SwiftPro Plumber & Water Heaters
4200 Lafayette Center Dr, Suite N, Chantilly, VA 20151
Virginia Class A contractor license #2705192276