Worried about mold in your air ducts? Here are some signs you shouldn’t ignore. Contact Thomas Hoffmann Heating & Air for a professional inspection today.
Mold is one of those household problems that often hides in plain sight, especially when it grows in places you can’t easily see, like inside your HVAC ductwork. Unfortunately, what you don’t see can still impact your health, air quality, and energy bills.
At Thomas Hoffmann Air Conditioning & Heating, we’ve helped countless St. Louis homeowners identify and resolve hidden mold issues inside their air systems. If you’re wondering whether there might be mold lurking in your air ducts, here’s what you need to know.
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!!!
Fast, friendly, professional service.
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!
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.
Excellent.
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!
Thank u
Response from the owner:Thank you, Connie, we appreciate your feedback and are glad to hear from you!
Courteous friendly and efficient! What else could you want!
Response from the owner:Thank you, Bob! We're glad you found our service courteous, friendly, and efficient – that's exactly what we strive for!
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!
Quick response time and great to deal with!
Response from the owner:Thank you, Pat! We appreciate your kind words and are glad to hear you had a positive experience with our team.
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!
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.
They came very fast to fix our AC and service was very good
Response from the owner:Thank you, Maria, for your kind words about our service; we're glad to hear you had a great experience!
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.
Nick zeroed right in on the problem with a slight leak and quickly provided a solution.
Response from the owner:Thanks, George, for your kind words! We're glad Nick could quickly address the issue for you.
I have complete trust in Thomas Hoffman AC . I have had multiple
technicians who are always polite and knowledgeable.
Response from the owner:Thank you for your trust in our team, Henry! We appreciate your kind words about our technicians.
Speedy and knowledgeable service!
Response from the owner:Thank you, Zach, for your kind words; we appreciate your support!
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!
Nick was a true expert in explaining our options for a new thermostat.
Response from the owner:Thank you, Robert, for your kind words about Nick's expertise; we're glad he could help you with your thermostat options!
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!
I've used these guys twice now and their response time is great, they are friendly, informative, and most importantly, effective. I'm calling these folks every time my furnace sounds weird.
Response from the owner:Thank you for the wonderful feedback, Greg! We're glad to hear that you've had such positive experiences with our team. Providing timely and effective service is our priority, and we're here whenever you need us. Looking forward to assisting you again!
Excellent place to work with and installation crew were A+. They were able to get my new AC and Furnace installed quickly. I have breathing issues and disabled so this was a GREAT experience. If you need AC or Furnace installed this is your place.
Response from the owner:Thank you, Tony, for your wonderful feedback! We're glad to hear that our installation crew made the process smooth and efficient for you. Your satisfaction means a lot to us, and we appreciate your recommendation!
Fast, super friendly, and reasonable prices keep us coming back.
Response from the owner:Thank you! We're so glad to hear that our speed, friendliness, and prices keep you coming back. We appreciate your support!
Zachary was very friendly, efficient and knowledgable. He was able to service both units in 1 hour. I would recommend Thomas Hoffmann A/C for any future needs for me.
Response from the owner:Thank you, Michael! We're glad to hear that Zachary provided you with friendly and efficient service. We appreciate your recommendation and look forward to assisting you with any future needs.
Great service and went the extra mile for us . We would most definitely use them again
Response from the owner:Thank you, Andre, for your kind words and for recognizing our efforts; we can't wait to serve you again!
Thomas Hoffman air-conditioning and heating is so wonderful and professional! Nick Hoffman was the technician that diagnosed my malfunctioning air conditioning system and determined how to fix it. He was so incredibly professional and even invited me to watch while he worked, and kindly explaining to me all the details about the problem and how he is fixing it. I am now a client for life with this company because of how professional, knowledgeable, and a delight to work with they are! I want to add that they prioritized helping me on the same day that I called and even was a holiday (and 90 degree heat out!), so that is another outstanding Effort from this amazing company! Thank you so much.
Response from the owner:Thank you, Carrie, for your wonderful feedback! We're delighted to hear about your positive experience with Nick and our team. Your satisfaction is our priority, and we're glad we could assist you on the same day. Welcome to our family of clients!
They were able to come out quickly to help when our AC went down in the heat! They were prompt, kind, knowleadgable, explained everything easily in ways I could understand, fixed the issue, and made the experience so easy! I felt comfortable with the technican in and around our home working. Nick took the time to answer some questions about an unrlated issue while there. They will always be who we call for our heating and cooling needs!
Response from the owner:Thank you, Erin, for your wonderful feedback! We're glad to hear that our team, especially Nick, was able to assist you promptly and make the experience comfortable and easy. Your trust in us for your heating and cooling needs means a lot!
I highly recommend Thomas Hoffmann for anything involving HVAC. The person replacing my furnace, Britton Buehrig, was Professional and took pride in his work. The job was very cleanly done.
Response from the owner:Thank you, Ray, for your kind words and recommendation! We're glad to hear that you were provided with professional service and a clean installation. Your satisfaction means a lot to us.
Excellent service. AC went out on a hot summer day, hooked up with them through Angi, and within 2 hours they had arrived and fixed the problem. Can't ask for more than that
Response from the owner:Thank you for your kind words! We're glad we could help you quickly on that hot summer day. Your satisfaction means a lot to us!
Nick Hoffman was great. He came short notice to fix a leaky air handler did it quickly and efficiently and also took a look at the AC plan on using them again for our service of our HVAC
Response from the owner:Thank you, Jenny, for your kind words about Nick and for trusting us with your HVAC needs; we're glad to hear he was able to assist you efficiently!
Super company to deal with. Always professional, knowledgeable and friendly. Zachery was my technician and explained everything he did throughly and in a manner I could understand. Very nice guy.
Response from the owner:Thank you, Maggie, for your kind words! We're glad to hear that Zachary provided you with excellent service and clear explanations. We appreciate your support and look forward to helping you again!
My a/c was not working correctly and I knew it needed to be serviced. The person came and cleaned what needed to be cleaned and he did what he could for the output. He was very professional and nice. We will definitely call them for our future needs.
Response from the owner:Thank you for the positive feedback! We're glad to hear that you were pleased with our prompt and friendly service. We look forward to assisting you again in the future!
Great service
Response from the owner:Thank you so much for your kind words! We're grateful for your support and delighted to hear you had a great experience.
Nick arrived to repair our ac earlier than expected. He quickly diagnosed and made the necessary repairs. The cost was reasonable. We will definitely contact Thomas Hoffmann for hvac services in the future..
Response from the owner:Thank you, Michael! We're glad to hear Nick provided prompt and efficient service, and we appreciate your trust in Thomas Hoffmann for your future HVAC needs.
We have used Thomas Hoffman Air Conditioning and Heating for AC issues for the last two years. We have been so happy with the service we have received both times. This year, we just needed a little maintenance as our unit wasn’t working to its full potential. I called first thing in the morning and was able to get a same day appointment! Nick was so personable and knowledgeable, and he got us back up and running and no time. Thank you again for saving us from the summer heat!! We are so grateful for the amazing customer service you guys provide!!!
Response from the owner:Thank you so much, Teri, for your kind words and for trusting us with your AC needs over the past two years; we're glad Nick could help get your unit back to its best, and we truly appreciate your gratitude for our service!
⚠️ Why Mold in Air Ducts Is a Big Deal
Your ductwork is the circulatory system of your home — if there’s mold inside it, spores can be pushed into every room whenever your HVAC system runs.
That can lead to:
- Aggravated allergies and respiratory issues
- Musty odors throughout your home
- Decreased air quality
- Long-term health risks, especially for children and the elderly
And because mold thrives in damp, dark environments, your ducts are the perfect hiding spot.
🔍 Signs You May Have Mold in Your Ductwork
While you might not see the mold directly, your HVAC system may be sending clear warning signs:
1. Musty or Earthy Odors When the AC or Heat Runs
If your home smells like an old basement every time the air turns on, mold or mildew in the ducts may be the culprit. This smell often worsens during humid summers in St. Louis. 🌧️
2. Allergy or Asthma Flare-Ups Indoors
Have you or your family noticed itchy eyes, sneezing, or shortness of breath indoors, especially when the HVAC is on? Mold spores circulating through your air supply can be a hidden trigger.
3. Visible Mold Around Vents or Registers
Sometimes, mold can start to appear around supply vents or on the ceiling nearby. This could be a sign it’s also growing inside the duct system.
4. Inconsistent Airflow or Unusual Humidity
Duct obstructions and moisture buildup from mold can interfere with airflow. If certain rooms feel more humid or aren’t cooling properly, mold might be part of the issue.
5. Recent Water Damage or Flooding
If your home recently experienced a leak, plumbing issue, or flooding — especially in the attic or basement — your ducts may have been exposed to moisture, creating the ideal breeding ground for mold.
🧪 How to Confirm Mold Growth
Because mold is often hidden deep within your ductwork, the only way to know for sure is to have a licensed HVAC technician or indoor air quality specialist perform a thorough inspection.
At Thomas Hoffmann Heating & Air, we use advanced tools and techniques to:
- Inspect deep within your ductwork
- Test air quality for contaminants
- Identify moisture sources
- Recommend cleaning or remediation solutions tailored to your system
🧼 Can Mold in Ducts Be Removed?
Yes — but it requires the right equipment and expertise.
Duct cleaning alone is not always enough. If mold is actively growing, it may require professional treatment, and the source of the moisture must be addressed to prevent its return.
We often recommend:
- Sealing duct leaks
- Installing a whole-home dehumidifier
- Upgrading air filtration or UV purification systems
🛡️ How to Prevent Mold in Your HVAC System
After remediation, prevention is key. Here’s how you can reduce the risk of mold coming back:
- Replace HVAC filters regularly
- Schedule seasonal maintenance and duct inspections
- Install a dehumidifier (especially in basements or crawlspaces)
- Ensure proper drainage from your AC unit
- Keep air vents open and unobstructed
🏡 Why St. Louis Homes Are Especially Vulnerable
The humid Midwest climate, combined with older home construction and basements, makes many homes in St. Louis naturally prone to moisture issues.
That’s why our team at Thomas Hoffmann specializes in whole-home air quality solutions designed specifically for our region, not just generic fixes.
