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4.7

(1.2k reviews)

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Avatar for Fresh Air Heating & Cooling
Fresh Air Heating & Cooling
4.8(
277
)

Serving O Fallon, MO and surrounding areas

Approved

In business since 1947

Free estimates

Emergency services offered

"Great Experience. I was concerned about the 22 yr age of our air conditioner able to keep working and wonder if a long wait time to get a product shipped like refrigerators last year, I called for a quote and within a week it was installed and working! Installers worked tirelessly until their work was done, clean and neat!"
Fresh Air Van
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+2

8 neighbors recently requested a quote
Recommended by92%of homeowners
Avatar for Anton's Plumbing, Heating/Cooling & Energy Experts
Anton's Plumbing, Heating/Cooling & Energy Experts
4.7(
513
)

Serving O Fallon, MO and surrounding areas

Approved (Corporate)

Super Service Award Winner

In business since 1979

Free estimates

Emergency services offered

"I always recommend Anton's to family and friends who need HVAC services. Their prices are reasonable, and their service is top notch! All of their technicians are very professional and considerate and they don't try to sell you things you don't need. Ronan just came out this morning to do our annual A/C inspection. The service was excellent as always. He took the time to explain everything and made recommendations. I never felt pressured, and I trust this company to take care of my HVAC needs. They've got a customer for life!"
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+18

Response time1 day
Response rate86%
16 neighbors recently requested a quote
Avatar for Liberty Heating & Cooling
Liberty Heating & Cooling
4.8(
46
)

Serving O Fallon, MO and surrounding areas

Approved

Super Service Award Winner

In business since 2017

Emergency services offered

Warranties offered

"Liberty did a fantastic job identifying and rectifying airflow problems with our existing Hvac system that was installed less than two years ago by another company. They were punctual, responsive and incredibly knowledgeable. I highly recommend them."
A/C replacement
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+10

6 neighbors recently requested a quote
Recommended by93%of homeowners
Avatar for Hosack Plumbing Heating & Cooling
Hosack Plumbing Heating & Cooling
4.8(
344
)

Serving O Fallon, MO and surrounding areas

Approved

In business since 2009

Warranties offered

Credit card accepted

"Awesom. Highly recommend Glen. We bought new refrigerator and needed new updated waterline installed. Since we had plumber in house wanted to update things we knew we needed done eventually."
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+2

Response time6 days
10 neighbors recently requested a quote
Recommended by93%of homeowners
Avatar for AAA Home Services
AAA Home Services
4.9(
9
)

Serving O Fallon, MO and surrounding areas

Approved

In business since 1970

Warranties offered

Small jobs welcome

"I highly recommend AAA home services. They installed a brand new HVAC system and the entire process was trouble free every step of the way. I have had them out to service the system twice a year and the scheduling to do so is easy and the service has been excellent. AAA home services has always communicated well and I have had them do exceptional plumbing work including the installation of a hot water heater. Thank you AAA home services."
AC units from American Standard
HVAC Installation
HVAC Installation
Avatar for Anton's Plumbing, Heating/Cooling Energy Experts
Anton's Plumbing, Heating/Cooling Energy Experts
4.6(
81
)

Serving O Fallon, MO and surrounding areas

Approved

In business since 2000

Free estimates

Emergency services offered

"Both the estimator Kevin the two installers who visited my home were very professional and kind. They answered all my questions and provided a very reasonable price for the installation of the attic insulation. I feel I was very informed on the federal rebate that was available for this installation, as well as on the recommendations of quantity of insulation I needed per residential standards and codes. I would recommend Anton and will use them in the future for my HVAC needs!"
Response time6 hrs
Recommended by95%of homeowners
Avatar for Aire Serv of St. Louis
Aire Serv of St. Louis
5.0(
5
)

Serving O Fallon, MO and surrounding areas

Approved

In business since 2024

Free estimates

Emergency services offered

Looking for reliable HVAC service in St. Louis? Aire Serv of St. Louis is your local expert for residential and commercial heating and cooling. From emergency AC repair during humid Missouri summers to furnace maintenance before the winter chill, our professional technicians are available to keep your home comfortable. We pride ourselves on transparent, upfront pricing, no overtime charges, and the "Done Right Promise." Whether you need a system replacement, duct cleaning, or a routine tune-up in Fenton, Webster Groves, or Kirkwood, we are the team you can trust. Breathe easy with Aire Serv—your comfort is our top priority. Call us today to schedule your service!

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Heating and Air Conditioning questions, answered by experts

If you’re trying to buy a new AC unit, there are a few crucial factors to consider. Look at the cooling capacity, the available warranty, the energy efficiency, and the type of unit. A ductless unit will cost more up front but may be a more viable option if you don’t already have ductwork. Additionally, a unit with better energy efficiency will cost less to run overall, saving you money on your monthly energy bill. 

If you’re shopping around for a rooftop AC unit, you may hear them referred to as “package units.” That’s because rooftop AC systems are all-in-one heating and cooling units that connect directly to your home’s ductwork. If your AC repair pro references a package unit, they are referring to the system on your roof.

Common signs of insufficient return air include uneven temperatures, with some parts of your home feeling hotter or colder than others, and noticeable differences in air pressure between rooms. You might also observe that more air is blowing in rooms closer to the AC unit. Leaky air ducts can also be a related issue or clue.

While many states do not have specific licensing requirements for HVAC companies, your local city or county might. It's always a good idea to check local requirements online and use a tool like Angi’s contractor license lookup to confirm that the company you’re considering is licensed. Regardless of licensing, you should always ensure the company you hire is fully insured to avoid potential lawsuits if a technician is injured on your property. Additionally, it is recommended to check if the company holds third-party certifications, such as North American Technician Excellence (NATE) certification or R-410A certification, which qualifies them to work with HVAC refrigerants.

Yes, you can build a deck over your outdoor HVAC unit, but you need to leave at least 5 feet of vertical clearance above the unit. If you don’t want your deck to be that high off the ground, you could build a floating deck in another part of your yard—again, as long as you leave at least 4 feet of horizontal space between the deck and your AC unit.

The O Fallon, MO homeowners’ guide to heating and air conditioning services

From average costs to expert advice, get all the answers you need to get your job done.