Is your AC filter getting dirty too fast? Here are some common causes and ways to keep your home’s air clean and your system running efficiently.
Have you ever changed your AC filter, only to find it clogged again just weeks later? You’re not alone. At Thomas Hoffmann Air Conditioning & Heating, we hear this question often from homeowners across the St. Louis metro area. A dirty AC filter isn’t just annoying — it can strain your system, spike your energy bills, and even affect your health.
Thomas Hoffman was very responsive to our after hours inquiry, even walked us through some trouble shooting over the phone. We provided pictures of the unit and they were able to quickly buy, schedule and install the part to keep our family warm!
Response from the owner:Thank you, Ali! We're glad to hear that Thomas was responsive and helpful in getting everything sorted out for you and your family. Your feedback means a lot to us!
Nick came by, identified the problem quickly and had it fixed. Great service!
Response from the owner:Thank you, Ted! We're glad to hear that Nick provided you with quick and effective service. Your feedback is greatly appreciated!
Great service. Responsive. Well trained technicians. Honest friendly and thorough. I highly recommend Tom Hoffmann and his team.
Response from the owner:Thank you for your kind words! We appreciate your recommendation and are delighted to hear about your positive experience with our team.
Ryan Taylor with Thomas Hoffman did an outstanding job in servicing our unit & explaining everything to me, especially how our humidifier worked, since we were new home owners & had not had one before. Thank you!
Response from the owner:Thank you! We're glad to hear that Ryan and Thomas provided you with excellent service and helped you understand your new humidifier. We appreciate your feedback!
Response from the owner:Thank you, Hank, for your wonderful feedback; we're glad you enjoyed the fast, friendly, and professional service, and we'll be sure to keep up the great work!
As always, the Hoffmann technician Zach was polite, professional, and efficient. Pricing is reasonable and even more importantly, they are dependable. I will continue to use Thomas Hoffman A/C and Heating.
Response from the owner:Thank you, Mark, for your kind words about our technician and for your continued trust in Thomas Hoffman A/C and Heating; we truly appreciate your support!
Response from the owner:Thank you, Brandon! We appreciate your kind words and are glad to hear about your positive experience with Hoffmann’s professionalism and thoroughness.
Response from the owner:Thank you, Pat, for your kind words about Giovanni; we appreciate your feedback and are glad to hear that he made a positive impression.
Our service technician arrived right on time and was professional, friendly, efficient and courteous. We couldn’t ask for more.
Response from the owner:Thank you for sharing your positive experience with our service technician! We appreciate your kind words and are glad to hear that you were satisfied with the service provided.
I'm a new customer and had my first appointment for furnace check.My tech was Zack and what a professional. He explained how he checked system and answered all my questions. This was a very good experience
Response from the owner:Thank you, Patricia, for your kind words! We're glad to hear that Zack provided you with a professional and informative experience during your furnace check. Your satisfaction means a lot to us!
Thomas Hoffman is a wonderful company to work with. Techs are knowledgeable, personable & efficient.
Response from the owner:Thank you, Christine, for your kind words about our team; we appreciate your feedback and are glad to hear you had a positive experience!
I called on December 25th at midnight and started leaving a message and Thomas Hoffman the owner called me back almost immediately. He said he would come out the next morning between 8:00 and 10:00 am snd he was promptly on time. He fixed my problem and while he was there I decided to get an estimate for a new furnace and air conditioning unit. The price was very reasonable and the installers one of them being his son were both very professional very courteous, polite, arrived on time and finished the same day. I enjoy knowing that I now have the support of Thomas Hoffman heating and air conditioning along with the peace of mind that comes with owning a Trane. Nothing stops a Trane.
Albert Koesterer
Response from the owner:Albert thanks so much for your kind reviews and your business. We truly appreciate it!!!
The Thomas Hoffmann team did a great job taking care of our semi annual HVAC maintenance. They not only worked with us to schedule the visit, but also did an excellent job sending us reminders on when they would be out.
Response from the owner:Thank you so much for the great review, Bob! We appreciate your support and are happy to hear you had a great experience!
Nick was excellent. Super profession, quick, and up front with the pricing (which was fair). Hopefully we don't need to call anyone to fix our AC again, but if we do - I'm calling Nick!
Response from the owner:Thank you, Layton, for your amazing review! We really appreciate your support and hope to be your first call for any future repairs!
Same day service. Technician arrived as scheduled. Replaced capacitor quickly. Friendly technician. Repair cost $429 seemed high for inexpensive part and 20 minutes labor.
Response from the owner:Thank you, Tom, for your feedback! We're glad to hear the technician was prompt and friendly, though we understand your concerns about the repair cost. We appreciate your insights and hope to serve you again in the future.
Response from the owner:Thank you so much, Al, for your excellent review; we truly appreciate your support and are glad to hear you had a great experience!
Thomas Hoffmann is the most professional and courteous of all the HVAC companies in St. Louis. It has kept my HVAC systems in good working order through the hottest and coldest days for many years.
Response from the owner:Thank you, Jonathan, for your kind words about our professionalism and courtesy; we truly appreciate your support!
I notified two companies at the same time regarding a malfunctioning AC unit and Wow! Super fast response from Hoffmann on a weekend no less, to fix our AC unit. Hoffmann’s tech responded to my call immediately and fixed our AC before Galmiche has even responded. Used to be a Galmiche customer, but will use Thomas Hoffmann from here on out!
Response from the owner:Thank you, Darlene, for your fantastic feedback! We're glad to hear that our team was able to respond quickly and resolve your AC issue. We appreciate your trust in us moving forward!
Ryan did a great job with my AC reinstall. Very knowledgeable company with Tom Hoffmann providing the engineering expertise.
Response from the owner:Thank you, Steve! We're glad to hear that Ryan did a great job on your AC reinstall, and we appreciate the shoutout to Tom's expertise. Your satisfaction means a lot to us!
These guy's are amazing same day service very well priced for the knowledge they have ask before doing anything to confirm they're my new go to
Response from the owner:Thank you, Cory! We're glad you found our service amazing and appreciate your kind words about our pricing and knowledge. We're here for you anytime!
My ac compressor was replaced. They always do a good job and they are always available when you need them.I think the price was a little too high since they only had to change the compressor in my unit. The compressor was under the warranty. Other than that Im very satisfied with the job the technician did.
Response from the owner:Thank you, Carlos, for your feedback and for recognizing the hard work of our technician; we appreciate your satisfaction with the job done and will take your pricing comments into consideration.
I was very pleased with your service. Prompt response would was most appreciated. The technician was very knowledgeable and prepared for the work. Also he was very personable and professional.
Response from the owner:Thank you, Richard, for your kind words; we appreciate your recognition of our technician's knowledge and professionalism, and we're glad you had a positive experience with our service.
Thank goodness for them coming out so quickly. Got our whole job done and we are COOL again. Thanks so much!!!
Response from the owner:Thank you, Sandy! We're so glad to hear everything got done quickly and you’re feeling cool again. We appreciate your kind words!
Had an amazing experience with Thomas Hoffman. They were very professional and solved the problem quickly. I would highly recommend!
Response from the owner:Thank you, Alex, for your wonderful feedback! We're glad to hear that Thomas was able to assist you so effectively. Your recommendation means a lot to us!
Zac did our service today. A very professional and courteous young man. He did a thorough inspection and cleaning on our HVAC system.
Response from the owner:Thank you, Tom, for your kind words about Zac's professionalism and thoroughness during your HVAC service; we appreciate your feedback!
Why Is My AC Filter Getting Dirty So Fast?
There’s no single answer — but there are common culprits we see all the time in Missouri homes:
1. You’re Using the Wrong Filter Type
Not all filters are created equal. Some filters (like high-MERV or HEPA) trap more dust and allergens — but that also means they clog faster. If you’re using a high-efficiency filter in a home that doesn’t need it, it may be overkill.
Tip: Ask a licensed HVAC technician to recommend the right filter for your system and lifestyle.
2. You’re Running Your System Constantly
St. Louis summers get hot — and when the AC runs non-stop, it pulls more air (and more dust) through the filter. That speeds up the clogging process.
Tip: Use a programmable thermostat to manage indoor temps efficiently. Also, make sure your system is properly sized — oversized units short-cycle, while undersized ones overwork.
3. You Have Pets
Dogs, cats, and other furry friends shed dander and hair, which your filter has to trap. Pet hair can coat a filter faster than you’d expect.
Tip: Change your filter more frequently if you have pets — especially during seasonal shedding.
4. Your Home Has Poor Air Circulation
Dust settles when air doesn’t move. If your home is tightly sealed or has blocked vents, your system may suck in more dust than necessary.
Tip: Keep return vents clear, use ceiling fans to improve circulation, and consider a home ventilation audit.
5. You Haven’t Sealed Your Ductwork
Leaky ducts can pull in dirt and insulation from unconditioned areas, such as attics or basements, sending it directly to your filter.
Tip: Have your ductwork inspected. Sealing leaks improves airflow, comfort, and efficiency.
6. You’re Renovating or Recently Did Construction
Home improvement projects release fine dust, drywall particles, and debris that quickly overwhelm air filters.
Tip: Use temporary high-efficiency filters during renovation and change them often.
7. Outdoor Air Quality Is Poor
Wildfires, pollen season, and local pollution all affect indoor air quality. Your filter works overtime when outside air is bad.
Tip: Keep windows closed on high-pollen or pollution days and consider using an air purifier for added protection.
How a Dirty AC Filter Affects Your HVAC System
If you’re thinking, “It’s just a little dust,” think again. A clogged air filter can cause serious HVAC problems:
❌ Reduced airflow, leading to poor cooling and uneven temperatures.
❌ Frozen coils that cause breakdowns or expensive repairs.
❌ Higher energy bills because your system works harder than it should.
❌ Dustier home and worsening indoor air quality.
❌ Shortened system lifespan due to excess wear and tear.
How Often Should You Change Your AC Filter?
Home Type
Suggested Filter Change Frequency
No pets, minimal dust
Every 2–3 months
One pet
Every 1–2 months
Multiple pets or allergies
Every 30 days
Post-renovation
Every 2–4 weeks
Still unsure? Ask Thomas Hoffmann AC & Heating to check it during your next maintenance visit.
✅ Schedule regular maintenance — our technicians can clean components, inspect your system, and suggest upgrades.
✅ Upgrade to a whole-home air purifier or UV system to reduce airborne particles before they even reach the filter.
✅ Seal your ducts and weather-strip doors and windows to keep out unwanted debris.
✅ Use high-quality, pleated filters that balance filtration with airflow — we can help you choose the best fit.
✅ Mark your calendar or set reminders to check your filter monthly.
Need Help? Call Your Local HVAC Experts
At Thomas Hoffmann Air Conditioning & Heating, we’ve served homeowners across St. Louis, Chesterfield, Kirkwood, Ballwin, and surrounding communities for decades. We’re locally owned — not a corporate chain pretending to be “local” — and we take pride in helping our neighbors breathe easier.
