Locally Owned · Serving O’Fallon & St. Charles County

HVAC Repair & Services in O’Fallon, MO

O’Fallon has grown into one of Missouri’s largest cities, and the furnaces and air conditioners installed during that building boom are aging right on schedule. Thomas Hoffmann, Master HVAC Engineer with 30+ years in the St. Louis metro, leads the team that keeps those systems running: honest repairs, careful replacements, and maintenance that earns its keep.

4.9 Google Reviews
30+ yrs experience
24/7 phones answered

Schedule Service in O’Fallon

Describe the problem in a sentence or two and we’ll handle the rest. Business-hours calls come back within 30 minutes, and same-day visits are booked whenever openings allow.

Gas furnace repair and replacement for O'Fallon, MO homes, Thomas Hoffmann Air Conditioning & Heating

The Boom-Era Furnace Problem

O’Fallon Grew Fast. Its Furnaces Are Aging Fast, Too.

Thousands of O’Fallon homes went up in the 90s and 2000s, and many still run the builder-grade furnaces and air conditioners installed on day one. Equipment like that often starts showing its age around the 15-to-20-year mark: ignition trouble, short cycling, rising bills. This is where 30+ years of hands-on diagnosis pays off. We tell you honestly whether the system has more good winters in it, and when it doesn’t, we put a repair price and a replacement quote side by side so the decision is yours.

Local

St. Louis Based

An independent local company serving St. Charles County, not a franchise wearing a familiar-sounding name.

30+

Every Kind of System

Three decades on gas, electric, and dual-fuel equipment, from original builder installs to today’s high-efficiency units.

Upfront

Clear Estimates

Pricing in writing before any work begins, so the bill at the end matches the number at the start.

24/7

Breakdowns Don’t Wait

Live dispatch around the clock, because equipment fails on holiday weekends more often than it should.

Urgent? Call Now.

Furnace out on a school morning? AC dead in a heat wave?

Call at any hour and a live dispatcher sorts the true emergencies from the can-wait-until-morning problems, then gets a technician headed to O’Fallon. And the rule that overrides everything: if you smell gas or a carbon monoxide alarm sounds, get everyone out of the house first and call from outside.

24/7 Emergency HVAC Service in O’Fallon Live answer, honest triage, fast dispatch.
Call (314) 471-7625

Straight From Customers

4.9 ★ on Google, One Honest Job at a Time.

Michael S.
2 days ago
Ryan has been a pleasure to work with. Unfortunately, to complete the installation of the contracted systems, there's still work to do getting the right vents in place, completing the thermostat placements, adjusting the airflow in the upstairs bedroom, etc. He's scheduled to come back next week and hopefully we can get this all finished.
Joe E.
3 days ago
Ryan was my service technician. I rate 10 stars ! Polite, knowledgeable and Honest !! Found the problem and heat back on. Excellent experience. Thank you Ryan !
Response from the owner:Thank you, Joe, for the 5-star review; your support means a lot to us!
Kathleen D.
4 days ago
Ryan was very professional, knowledgeable, and thorough. I was able to get an appointment the same day during a biter, snowy day.
Response from the owner:We are so glad to hear you had a pleasant experience, Kathleen!
James H.
4 days ago
Came out immediately after a time slot opened and fixed the AC issue.
Response from the owner:Thank you, James, for your kind words! We're glad we could address your AC issue promptly.
Tom S.
5 days ago
They were good and did an exce llent job. Thank you
Response from the owner:Thank you for the 5-star rating, Tom!
Matthew K.
6 days ago
Great work! They cleaned up my ducts and made it more efficient without trying to upsell me on random things. Will use them again!
Chris B.
7 days ago
Nick was professional, very knowledgeable, courteous and efficient. Nice people in the office too.
Mark T.
1 week ago
This company is the best! Had another service our HVAC and had nothing but issues. Zach from Hoffman is courteous and efficient. Highly recommend this company
Response from the owner:Thank you, Mark! We're glad to hear you had a great experience with Zach and appreciate your recommendation. Your support means a lot to us!
Darrell B.
2 weeks ago
Came next day after call. May the repair quickly
Response from the owner:Thank you, Darrell! We're glad to hear that we could assist you promptly and efficiently with your repair. Your satisfaction means a lot to us!
Teresa F.
2 weeks ago
Ryan arrived 20 minutes early. A great start to our day as we had a plumber coming today as well. They did overlap, but Ryan was thorough, efficient and gave us a clean bill of health on our furnace in about 45 minutes. WE LOVE THOMAS HOFFMANN AIR CONDITIONING AND HEATING. Oh and get the combo service plan for both your furnace and AC annual service. Very reasonable.
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.
Brandon B.
2 weeks ago
Zach was incredibly friendly, professional, and easy to work with. They provided high-quality work and clearly take pride in what they do. The entire experience was smooth and pleasant from start to finish. It’s refreshing to work with people who are not only skilled at their job but also genuinely kind and helpful. I highly recommend them!
Response from the owner:Thank you, Brandon! We're glad to hear you had a smooth and pleasant experience with Zach. Your kind words about their professionalism and kindness mean a lot to us. We appreciate your recommendation!
john J.
2 weeks ago
Got a checkup on the hottest day of the year and everything is working fine. Great service.
Response from the owner:John, thank you so much for the nice review! We are so happy to hear you had a positive experience.
Brian B.
3 weeks ago
Tech was on time and stayed till they were finished. He was very thorough listen to our concerns and had open and honest suggestions all while having casual conversation and making me and my wife feel comfortable.
Response from the owner:Thank you for recognizing our team's punctuality and dedication!
Premchand T.
3 weeks ago
Excellent service
Response from the owner:Thank you, Premchand, for your kind words about our service! We appreciate your feedback and are glad you had a great experience.
Dale C.
3 weeks ago
I love dealing with this company. Our tech, Zach, is professional and friendly. I love the level of communication from Thomas Hoffman: from the text/email reminders to schedule an appointment to the update of the appointment itself. Highly recommend this company!!
Response from the owner:Thank you, Dale, for your wonderful feedback! We're glad Zach could assist you effectively, and we appreciate your kind words about our communication and service.
Thomas E.
3 weeks ago
Very fast response and professional service.
Response from the owner:Thank you, Thomas! We appreciate your kind words about our fast response and professional service.
Kay H.
3 weeks ago
Zach came around 9:00 the early part of my window. It was my annual checkup and he said everything looked good. I will be moving out of state soon but appreciate your past service.
Response from the owner:Thank you so much for the great review, Kay. We truly appreciate your business!
William H.
3 weeks ago
Zach was great. He helped me better understand my systems and their operating systems.
Response from the owner:Thank you for the 5-star review, William. We are happy to hear Zach took good care of you.
Thomas E.
3 weeks ago
They installed our system and came out to check on a concern promptly and didn’t charge us.
Response from the owner:Thank you, Thomas! We're glad to hear that our team addressed your concern quickly and without any charges. Your satisfaction means a lot to us!
Pat Keith T.
4 weeks ago
Zachary is great! We purchase Hoffmans maintenance plan - they come when needed
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.
Beth R.
4 weeks ago
Competence and knowledge have been my experience.
Response from the owner:Thank you, Beth, for sharing your experience; it means a lot to us!
Becky W.
4 weeks ago
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.
Frank P.
4 weeks ago
From the phone to the completion of the job everyone is so polite and informative. I had Giovani as our representative and he was very informative and professional, and knew exactly what the problem was. Thanks so much.
Response from the owner:Thank you for the kind review, Frank! We appreciate you and your business.
Adi S.
1 month ago
Our AC condenser and coil were swapped out. The company did a very good job with staff that were most professional. Would happily recommend their company and keep them for all my annual maintenance work. I stress their staff is very knowledgeable and professional.
Response from the owner:Thank you, Adi! We're glad to hear you had a positive experience with our team and appreciate your recommendation. Your kind words about our knowledgeable and professional staff mean a lot to us.
Chris S.
1 month ago
great people
Response from the owner:Thank you, Chris! We appreciate your kind words about our team.

Common Questions

O’Fallon HVAC Questions, Answered Without the Runaround

Do you offer emergency HVAC service in O’Fallon?

Yes, 24/7 including weekends and holidays. Call (314) 471-7625 and a live dispatcher will gauge the urgency and get a technician assigned as quickly as the schedule allows.

Do you cover all of O’Fallon’s neighborhoods?

Yes. From WingHaven and Twin Chimneys to the established streets near Highway K and Mexico Road, we work across the whole city, in newer builds and older properties alike.

My furnace keeps turning on and off. What does that mean?

Short cycling can have simple causes, like a clogged filter, or bigger ones, like an overheating heat exchanger, a failing sensor, or an oversized system. It’s worth diagnosing promptly because it drives up bills and wears parts faster. We find the actual cause before recommending anything.

Do you handle ventilation and indoor air quality?

Yes. Newer, tightly sealed O’Fallon homes often trap stale air, humidity, and allergens. We assess ventilation and can add filtration, humidity control, or fresh-air solutions matched to the house and the family living in it.

Should I replace my furnace and AC at the same time?

Often it makes sense when both are similar in age, since matched systems tend to run more efficiently and installation costs overlap. But it isn’t automatic. If one unit has real life left, we’ll say so and price the options separately so you can compare.

Which communities near O’Fallon do you serve?

Lake St. Louis, Dardenne Prairie, St. Peters, Cottleville, Wentzville, St. Charles, and the rest of the St. Louis metro.

O’Fallon Comfort, Handled by People Who Answer.

One locally owned company, 30+ years of St. Louis HVAC experience, estimates in writing, and a phone answered at every hour of every day.