Don’t let something as simple as a dirty air filter reduce your comfort or drive up your bills. Call us today to keep your HVAC system clean.
Changing the air filter is one of the simplest yet most important maintenance tasks for your home’s HVAC system. But despite how easy it is, it’s also one of the most commonly overlooked. A dirty air filter doesn’t just affect your air quality—it can lead to higher energy bills, poor performance, and costly repairs.
If you’re a homeowner in St. Louis or surrounding areas like Ballwin, Kirkwood, or O’Fallon, this guide will help you spot the warning signs of a dirty filter and show you how to fix the problem fast.
These guys are pros. Techs are friendly, listen and explain what they are doing. Office staff is responsive. Fast service....
Response from the owner:Thank you, Clark, for your kind words! We're glad to hear our techs and office staff made your experience a great one. Your feedback means a lot to us!
Excellent service. A/C went out on a weekend. Called them on Saturday morning, they were out within about 2 hours. The fix was easy enough, and he even had the part in the truck! I recommend this company for all of your HVAC needs
Response from the owner:Thank you, Elaine! We're glad to hear you received prompt service and that the fix was smooth. Your recommendation means a lot to us!
The service technicians are very courteous and communicate well with the customer. They let you know what, if any, problems are found, the options, and the cost of the repair(s). Quick and efficient.
Response from the owner:Thank you for recognizing our service technicians' courteous and effective communication, we appreciate your feedback!
These guys were great. Quick to return my call. Up front pricing. Great work on the installation. And the installers were nice and friendly. Highly recommend Thomas Hoffmann.
Response from the owner:Thank you, Steve! We truly appreciate your kind words and are glad to hear you had such a positive experience with our team and Thomas Hoffmann. Your recommendation means a lot to us!
Hoffmann came out the same day I called them because our AC was out. The technician, Ryan, was able to get the system running again, was polite and responded to my questions. We’re off to a good start!
Response from the owner:Thank you, John! We're glad to hear Ryan was able to help and that you’re off to a good start with your AC. We appreciate your feedback!
Thomas came over promptly I spoke with him about my concerns with my unit. Immediately got to work trouble shooting and resolved my issues. A+
Response from the owner:Thank you, James, for your kind words and for recognizing Thomas's promptness and dedication in resolving your concerns; we appreciate your feedback!
We have called Thomas Hoffmann many times and they are very prompt and very professional.
Response from the owner:Thank you, Vicki, for your kind words about Thomas Hoffmann's promptness and professionalism; we truly appreciate your feedback!
Not a customer, but witnessed one of their technicians have an episode of road rage in Clayton. I would be concerned about letting them into my house/business.
We really trust Thomas Hoffman AC and Heating. Nick Hoffman has serviced our units several times now and he is professional, knowledgeable and very easy to work with. He comes on time, so we don’t have to schedule a long waiting period. We would highly recommend this company.
Response from the owner:Thank you, Greg, for your kind words and for trusting us with your AC and heating needs; we’re glad to hear that Nick has provided you with such great service.
We’ve been looking for a locally owned small HVAC dealer for a few years. And we found it with Thomas Hoffmann Air Conditioning & Heating. We love their service technicians. They come on time, they know what they are doing, they don’t upsell you on every appointment and they like working for Thomas Hoffmann. A happy employee makes for a happy customer.
Response from the owner:Thank you, Mary, for sharing your wonderful experience with us; we're glad to hear you appreciate our technicians and their commitment to great service!
I called on a Monday morning as air conditioning was blowing warm air. They were able to come to my house very early afternoon and fixed the problem. Would highly recommend and will use them again.
Response from the owner:Becky thank you so much for your great review. We appreciate your business and your kind words.
Response from the owner:Thank you, Margaret! We appreciate your kind words and will make sure to pass along your praise to Nick for his excellent service.
I am very pleased with the service provided. , especially the quick response to my request . The technician came in themorning and had my cooling system repaired within an hour. Thank you !
Response from the owner:We're delighted we could promptly assist you on a Sunday morning and fix your cooling system efficiently. Thank you!
Here on time, worked fast. Always pleasant and great answering questions. Zach always does a great job.
Response from the owner:Thank you, Debra, for your kind words; we're glad to hear Zach made a positive impression and that you had a great experience with our team!
Extremely quick response for appointment and did quick fix for our furnace and heat is working great !
Response from the owner:Thank you for your kind words! We're glad to hear our team was able to respond quickly and get your furnace working great. We appreciate your feedback!
They were timely, polite, professional and they saved us from too much sweating. In a field full of pompous and arrogant technicians, these guys take the time to explain what is wrong and how they are correcting it. Other folks just assume you are incompetent but these folks take the time to educate. Cannot recommend highly enough.
Response from the owner:Thank you for your kind words! We truly appreciate your feedback and are glad we could provide you with a positive experience.
I would like to have a receipt for my payment which I did not receive. On a positive note he was very punctual very early actually he did his job and was very professional and I'm hoping and praying this took care of the issue thank you and I would not hesitate at this time to use your services
Response from the owner:Thank you, Mark, for your feedback and for highlighting the punctuality and professionalism of our team; we appreciate your support and will ensure you receive your receipt promptly.
Our experience with them was fantastic all the way through! Not only were they able to get to our business that day but the customer service from the phone call to the on-site service was professional and quick. We'll definitely be using Thomas Hoffmann Air Conditioning and Heating in the future.
Response from the owner:Thank you, Michelle, for your wonderful feedback! We're glad to hear about your fantastic experience and appreciate your kind words about our team's professionalism. We look forward to serving you again in the future!
I couldn’t be happier with the service from Thomas Hoffmann Air-Conditioning! From the moment I called, the team was professional, responsive, and truly knowledgeable. Thomas personally made sure everything was handled with great attention to detail. The installation was smooth, efficient, and the quality of the work exceeded my expectations. It’s rare to find a company that is both skilled and genuinely cares about their customers. I highly recommend Thomas Hoffmann Air-Conditioning to anyone looking for honest, reliable, and top-notch service. They’ve definitely earned a loyal customer!
Response from the owner:Thank you, Rick, for your kind words and for recognizing our team's hard work; we're grateful for your support and thrilled to have earned your loyalty!
Amazing service from Thomas Hoffmann! They made space in their schedule to come out the next day to fix our air conditioner. They were on time, honest and fixed the problem on the spot. Thank you!
Response from the owner:Thank you, Ashley! We appreciate your kind words about our team's service – it's great to hear we could help you so quickly.
Fast efficient service. Both of the gentlemen that came to my home were very help and informative not to mention polite. It’s difficult to get service advisers to appear at your home when scheduled most times they’re late or don’t show up at all. Not an issue with this team on time, clear diagnosis, quick repair. I would definitely use Thomas Hoffmann Air Conditioning again. I recommend them highly.
Response from the owner:Thank you, Anna, for your wonderful feedback! We're glad to hear that our team provided you with timely and helpful service, and we appreciate your high recommendation.
First visit for my maintenance program. Arrived on time. Very polite to talk to. They discussed what they did and everything was good. They were professional. I would recommend this company to everyone.
Response from the owner:We're delighted to hear about your positive first visit experience with us! Thank you for recommending our services.
Very knowledgeable. Very professional. Tom was very thorough and finally confirmed the issues in the system that no one else bothered to check.
Response from the owner:Thank you, David, for your kind words; it's great to hear that Tom's thoroughness made a difference in addressing the issues in the system. We look forward to working with you in the future!
Why Air Filters Matter
Your HVAC filter is the first line of defense for your heating and cooling system. It traps:
When the filter becomes clogged, it restricts airflow and causes your system to work harder, leading to a chain reaction of problems—from decreased indoor air quality to system breakdowns.
Top Warning Signs of a Dirty Air Filter
1. Reduced Airflow
If your system seems to be blowing less air than usual, a clogged filter may be the culprit. Reduced airflow indicates that your HVAC struggles to circulate air through the dirty filter.
2. Hot or Cold Spots in the Home
Uneven temperatures between rooms often indicate that the HVAC system isn’t circulating air efficiently, frequently due to filter blockage.
3. Unexplained Increase in Energy Bills
Dirty filters force your system to run longer to reach the desired temperature. Over time, this leads to increased energy usage and higher utility bills, especially during St. Louis’s hot summers and frigid winters.
4. More Dust Around the House
Are you dusting more than usual? A clogged air filter can’t effectively trap particles, allowing dust to circulate and settle on your furniture and floors.
5. Musty or Stale Odors
When the filter is dirty, moisture and debris can create a breeding ground for bacteria or mold, leading to unpleasant smells whenever the system is on.
6. Frequent HVAC Cycling
Short cycling—when your system turns on and off frequently—can indicate that restricted airflow affects your system’s ability to maintain consistent temperatures.
7. System Overheating or Freezing Up
In extreme cases, restricted airflow can cause your furnace to overheat or your AC coils to freeze, leading to costly repairs or even full system shutdowns.
How Often Should You Replace Your Air Filter?
There’s no one-size-fits-all answer, but here are general guidelines for St. Louis homeowners:
Home Type or Condition
Filter Replacement Frequency
Standard home, no pets
Every 90 days
One pet
Every 60 days
Multiple pets or allergies
Every 30–45 days
Smoking indoors
Every 30 days
High allergy season (spring/fall in STL)
Every 30–45 days
How to Check If Your Filter Is Dirty
Turn off your HVAC system for safety.
Locate and remove the filter (usually behind a return vent or inside the furnace).
Hold it up to a light source. If you can’t see light through it, it’s time to replace it.
The Long-Term Costs of Ignoring a Dirty Filter
Neglecting your air filter may seem minor, but it can lead to:
Reduced system lifespan
More frequent breakdowns
Poor indoor air quality
Increased energy bills
More allergens and contaminants in the home
Need Help Changing Your Filter or Improving Air Quality?
Don’t let something as simple as a dirty air filter reduce your comfort or drive up your bills. Whether you’re due for seasonal maintenance or need help picking the right filter, Thomas Hoffmann Air Conditioning & Heating is here to help.
At Thomas Hoffmann Air Conditioning & Heating, we pride ourselves on being a locally owned and operated HVAC company. With more than 30 years of experience and a master technician and mechanical engineer as our owner, we can replace, repair, and maintain your business or home’s HVAC system.
