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.
Extremely thorough and educational. They do a wonderful job of explaining everything and making sure I was comfortable knowing how the systems worked in my house!
Response from the owner:Thanks for the great review, Matthew! We appreciate your support.
I noticed a strange noise that I was concerned was linked to my furnace. I called Thomas Hoffman Heating & Cooling and Nick came right out. He was very thorough checking all components. Thankfully all checked out for us this visit. Definitely recommend Thomas Hoffman Heating & Cooling!
Response from the owner:Thank you so much for the kind review, Abby! We appreciate your business and look forward to servicing you in the future.
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!
Got a quote over the phone. Everything was explained thoroughly. Dakota, my technician arrived and on time, was very professional and knowledgeable. He didn’t try to upsell or change anything. He did a great job. We can already tell the difference since the ducts and vents were cleaned. Would recommend an use Hoffman again in the future.
Response from the owner:Happy to hear you had a pleasant experience using Thomas Hoffmann!
The technician, Ryan, was knowledgeable and helpful in identifying the issue with our mini split AC unit. They are the second company we called after issues with the first and will be using Hoffmann again.
Response from the owner:We are so happy to hear your experience with Thomas Hoffmann was pleasant. Thank you for your kind review, & we look forward to working with you in the future!
woke up to a very cold house, called Thomas Hoffmann, they were able to come out a couple of hours later and get the issue resolved. Always trust them, they have always been quick to respond and get either the heating or ac issue fixed that day. Also a great price!!!! give them 10 stars if i could, Thank You JS
Response from the owner:Thank you for the kind review, Jim. We are happy to hear that you had a positive experience working with Thomas Hoffmann!
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 technician Giovanni was excellent and on time very professional and efficient and knowledgeable of the project at hand ,gave great advice but most of all did great work 👏 thank you .
Response from the owner:We are so happy to hear you had a great experience, Sam! Thank you for the review, and thank you for your business.
Your service technician was very professional and knowledgeable. And did not appear to try to give me bogus information. I truly appreciate his honesty because several other companies did not appear to be honest, obviously wasn’t honest, my gut feeling told me they were not honest and tried to get me to spend $10,000 for a problem that was much simpler to fix. I look forward to you servicing all my properties, and possibly those of the rest of my family.
Response from the owner:Thank you so much for the kind words and great review! We appreciate your support.
Very prompt, communication was great, and the workers were very polite. I highly recommend them!
Response from the owner:Thank you, Lianne! We're glad to hear that you had a positive experience with our team and appreciate your high recommendation.
Water heater repaired, appointment done the same day, effective, courteous
Response from the owner:Thank you, Leticia! We appreciate your kind words and are glad to hear that the water heater was repaired promptly and effectively. Your satisfaction means a lot to us!
The service tech Giovanni did a fantastic job. Our gas fireplace is working like new again so we’re ready for the cold weather!
Response from the owner:Thank you, Mr, for your fantastic review! We're glad to hear Giovanni provided you with excellent service and professionalism. Your recommendation means a lot to us!
⭐️⭐️⭐️⭐️⭐️ If I could give 10 stars, I absolutely would.
Last night our furnace went out unexpectedly, and with three kids in the house, the temperature dropped fast. Giovanni went above and beyond in every way possible. Instead of charging me a late-night service fee, he simply asked, “Are you decently handy?” and offered to walk me through some troubleshooting steps to get our heat back on so my children wouldn’t have to sleep in the cold.
Not only did he guide me through the process, he even FaceTimed me and showed me exactly what to take apart, how to put it back together, and what signals to watch for. It felt like having a real technician standing right next to me the entire time. Thanks to him, our heat was restored within minutes.
In a world where true customer service is hard to come by, Giovanni is a rare find. It is a guaranteed fact that any future repairs, maintenance, and the new heater/AC system we’ll be needing this coming summer/fall will absolutely be done through him. His honesty, kindness, and expertise have earned our business for life.
Highly, highly recommend.
Response from the owner:Thank you, Jeff, for sharing your experience! We're so glad to hear Giovanni was able to help you and your family during that tough situation. Your recommendation means a lot to us, and we appreciate your trust in our services for the future!
My neighbor referred these guys to me when had water heater problem. Previous company told me I needed to replace it. Tom’s technician fixed it for less than $200. This was over 2 years ago and have been using their service ever since. They are very trustworthy.
Response from the owner:Thank you, Mary, for sharing your experience and for trusting us with your water heater issue; we're glad our technician could help and that you've continued to rely on our services!
I called this company earlier today because I was having a bunch of issues with my HVAC system. They were incredibly friendly and walked me through troubleshooting step by step over the phone. They didn’t even charge me for the call. Thanks to their honest advice, I was able to get things running smoothly again. Really grateful for their help and would definitely recommend them if you want straightforward and trustworthy service. Five stars all the way!
Response from the owner:Thank you so much for the glowing review, Hector! We appreciate your business and look forward to working with you in the future.
Nick did not set current time. — Monday Hoffmans Zach came to fix correct time. We DID NOT want a timed thermostat — we prefer to set temperatures manually
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.
Clear communication about arrival, service and costs.
Response from the owner:Thank you, Margaret, for your kind words! We appreciate your feedback on our clear communication and are glad you had a positive experience.
I will highly recommend this business for your air and heater repair. Prompt, knowledgeable and courteous service.
Response from the owner:Thank you, Judy, for your kind words and recommendation! We're glad to hear you were pleased with our prompt and courteous service.
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!
Ryan was knowledgeable and figured out why our furnace wasn’t working and repaired the problem
Response from the owner:So happy to hear you had a good experience with the team here at Thomas Hoffmann, Jo! Thank you for your support.
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.
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