At Thomas Hoffmann Air Conditioning & Heating, we’ve seen it all. Contact us today by calling (314) 471-7625 or using our contact form.
There’s nothing worse than waking up on a cold Missouri morning, cranking up the thermostat, and feeling cold air blowing from your vents. If your furnace is supposed to be keeping your home warm and cozy, but instead it’s acting like an AC unit, don’t panic—several common causes could explain the issue, many of which are quick to fix.
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.
As always, the Hoffmann technician 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!
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.
Zachary was very knowledgeable and informative! Highly recommend!
Response from the owner:Thank you, Beth! We're so glad you found Zachary knowledgeable and informative—we appreciate your recommendation!
1. Thermostat Settings Are Incorrect or Misconfigured
Before jumping to conclusions about your furnace, always start by checking your thermostat. A simple setting issue might be the root of the problem.
What to Check:
Is the thermostat set to “ON” instead of “AUTO”? If so, the blower may run continuously—even when the furnace isn’t heating.
Is the temperature setting too low?
Are you accidentally in “cool” mode?
2. The Furnace Hasn’t Warmed Up Yet
Sometimes, it’s just a matter of patience. If your furnace just kicked on, it may take a minute or two for warm air to start circulating.
3. Dirty or Clogged Air Filter
A dirty filter can restrict airflow, cause overheating, or trigger your furnace’s safety mechanisms. This might make the system shut off the burners while the blower continues to run, resulting in cold air.
Symptoms:
Weak airflow
Increased energy bills
Furnace short cycling
4. Pilot Light or Ignition System Failure
If your furnace uses a pilot light (common in older systems) or a hot surface igniter, the burners may fail to ignite, leaving you with cold air blowing through the system.
Signs of Ignition Problems:
You hear the blower running, but no whoosh of flame
No visible flame through the inspection window
Error codes on modern control boards
5. Flame Sensor Is Dirty or Malfunctioning
Modern furnaces have a flame sensor to confirm that gas is being burned correctly. If it’s dirty or defective, it may shut down the burners to prevent unsafe operation, leaving just the fan running.
Common Symptoms:
Furnace turns on briefly, then shuts off
Cold air blows intermittently
Multiple restart attempts
6. Overheating or Limit Switch Tripped
If your furnace overheats, a safety switch (limit switch) may shut off the burners while keeping the fan running to cool the unit down. This can happen due to airflow blockages, dirty components, or mechanical failure.
7. Leaky or Disconnected Ductwork
Even if your furnace is producing heat, damaged or poorly sealed ducts can cause heat loss before the air reaches your vents, especially in unconditioned spaces like attics or crawl spaces.
Signs:
Cold air from a few vents, but not all
Uneven temperatures across rooms
Higher energy bills
8. Fuel Supply or Gas Valve Issues
If you have a gas furnace and it’s not producing heat, the gas supply may be off, or the gas valve could be faulty.
9. Your Furnace Is Reaching the End of Its Lifespan
If your furnace is more than 15–20 years old, recurring issues like cold air, uneven heating, or cycling could be signs it’s time for an upgrade.
When to Call the Experts
Some furnace problems have simple fixes, but others signal more serious mechanical issues or potential safety hazards. If you’re not comfortable troubleshooting or have tried these tips without success, call in the pros.
Thomas Hoffmann Air Conditioning & Heating offers:
Emergency heating repair across the St. Louis metro
Expert diagnostics for all major furnace brands
Transparent pricing and no-pressure service
Contact Thomas Hoffmann Air Conditioning & Heating Today
A furnace blowing cold air isn’t always a disaster—but it’s not something to ignore. With a bit of troubleshooting and the right support, you can quickly and safely restore comfort to your home.
