We fix what's broken, fast, and we don't disappear after the invoice. Same-day appointments available across O Fallon and the surrounding zip codes.
No automated menus for emergencies — a real person handles the call.
Ask as many questions as you want; we'd rather over-explain than leave you unsure.
Most repairs are completed same-visit, and we test the system before we leave to confirm it's actually holding.
Leonard HVAC grew one honest service call at a time in communities like O Fallon. Our crews carry manufacturer certifications across the major residential and commercial equipment lines.
You won't find us buried under layers of call-center scripts — we're the company that tells you what actually needs fixing instead of what pads the ticket. Licensing and insurance aren't optional line items for us, and we keep that documentation available on request for every job, residential or commercial.
We know which neighborhoods run on older ductwork and which subdivisions were built with newer high-efficiency systems. That local knowledge shapes how we diagnose problems — it's the difference between a tech who's guessing and a tech who's seen your exact situation a hundred times before.
Ask around O Fallon and you'll hear the same complaint about a lot of HVAC companies. That's the gap we built Leonard HVAC to close. We'd rather lose a job to a lower bid than win one by cutting corners on the diagnosis, because a customer who trusts us once tends to call us again — and O Fallon is a small enough community that reputation travels fast.
That local context saves time on every call, because we're not starting from zero on basic questions about your neighborhood or your system. We keep parts inventory stocked based on what actually fails most often on O Fallon's housing stock.
We cover the full range of heating, cooling, and air quality work O Fallon properties actually need.
A dead system in the middle of a heat wave or a cold snap isn't just inconvenient — it can be a real safety issue for kids, pets, and older residents. Our O Fallon dispatch team prioritizes no-heat and no-cooling calls so a technician is diagnosing your system as fast as physically possible.
We keep the truck stocked with the parts that fail most often on the equipment common to O Fallon homes, which is exactly why most repairs don't require a return visit.
Not every repair call ends in a repair — sometimes the honest recommendation is a properly sized replacement. We walk O Fallon homeowners through load calculations so the new system is sized correctly for the actual square footage before a single piece of equipment gets ordered.
We protect floors and entryways during the install and haul away the old equipment so you're not left dealing with disposal.
Downtime in a commercial space costs money every hour a system is offline. Our commercial division services rooftop units and package systems across O Fallon, with after-hours work to avoid disrupting business.
Our commercial techs are trained to work around your customers and staff, scheduling noisy or disruptive work outside peak hours whenever possible.
A seasonal tune-up catches the kind of wear that turns into a mid-summer no-cool call. Beyond standard tune-ups, we also handle indoor air quality upgrades for homes with allergy or asthma concerns for O Fallon households that want more than just temperature control.
A tune-up typically takes under an hour and covers the checkpoints most likely to catch a problem before it becomes a breakdown.
This is the standard every O Fallon technician on our team is held to.
Every repair comes with a workmanship warranty explained in plain terms before we leave.
We quote a flat rate before work begins and that number doesn't change once you approve it.
If anything feels off after we leave, one call gets a tech back to your O Fallon address.
A little attention to how your system is running can save you a lot of money and discomfort.
A healthy system runs with a consistent, low hum — banging, screeching, or grinding usually points to a loose part or failing motor.
Weak airflow from the vents often traces back to a clogged filter, a failing blower motor, or leaking ductwork.
Gradual efficiency loss is easy to miss month to month, but it adds up fast over a season.
A system that won't hold a steady cycle is often fighting a sizing issue, a thermostat problem, or a refrigerant imbalance.
A burning smell should never be ignored — it can indicate an electrical issue that needs immediate attention.
If you're calling about the same problem every few months, the underlying cause likely hasn't been fully addressed.
No inflated "emergency surcharge" games — the number we quote is the number you pay.
Because our trucks are stationed near O Fallon, we're rarely far from your address.
Parts and labor are backed by warranty terms explained in plain language.
Our techs recognize brand-specific quirks instead of learning your system on the job.
You make the final call — we just make sure you have the full picture.
We'll walk you through what's actually available before you decide.
Every review below reflects an actual service call in the O Fallon area.
"Our AC quit on the hottest weekend of the year and they had a tech out within a couple of hours. No pressure to buy a whole new system when a repair was all we needed."
"Scheduled a fall tune-up and they caught a cracked part before it became a real problem. Never once felt like I was being upsold on something I didn't need."
"Explained the sizing calculation so I understood why they weren't just installing the same unit again. Would recommend to anyone in O Fallon needing a real replacement, not a patch job."
"As a property manager, having a company that actually answers after-hours calls is rare. Now our go-to for every property in the portfolio."
"The estimate matched the final invoice exactly, down to the dollar. My energy bill dropped noticeably the first month with the new system."
"Diagnosed a failed capacitor and had it swapped within the hour. This is the company I'm saving in my phone now."
Understanding what typically fails helps homeowners know what to watch for and when a repair call is worth making before things get worse.
O Fallon's seasonal swings put real stress on a system that isn't maintained regularly. Filters should be checked monthly during heavy-use seasons and replaced roughly every 60-90 days depending on your household and any pets.
Setting a programmable or smart thermostat to a consistent schedule reduces the number of times the system has to work hard to catch up to a big temperature swing. None of this replaces a professional tune-up, but it does reduce the wear that leads to premature breakdowns between visits.
We also service package units common on manufactured and modular homes throughout the O Fallon area. If your system was installed by a different company entirely, that's not a problem — we service equipment regardless of who originally put it in, and we'll pull the model and serial information to confirm parts compatibility before any repair begins.
We don't outsource dispatch to a call center that's never met our technicians.
Over a decade in residential heating and cooling, with a focus on load calculations and full system replacements.
Runs point on overnight and weekend emergency calls throughout O Fallon.
Experienced with the light industrial and retail equipment common across the area.
Standard appointments are usually scheduled within 24-48 hours, while true emergencies jump the queue.
Yes — every job gets a clear quote before any repair work begins, so there are no surprise line items on the invoice.
Yes, no-heat and no-cool situations are treated as priority calls regardless of the hour.
Yes — licensing and insurance documentation is available on request for any job, residential or commercial.
Our technicians walk you through the actual numbers — repair cost versus remaining system life versus new equipment efficiency — before making a recommendation.
Yes, our maintenance plans include seasonal tune-ups, priority scheduling, and discounted repair rates for members.
Our dispatch area extends throughout the greater O Fallon region and nearby towns within O Fallon, MO.
Yes, we run separate residential and commercial divisions, both fully licensed and equipped for their respective equipment.
If parts require special ordering for a less common brand, we'll communicate that timeline upfront.
Ask about financing during your in-home estimate to see what fits your situation.
Twice-yearly maintenance is the standard we recommend given the temperature swings the area sees.
Check that the thermostat has power and the batteries aren't dead, and check your breaker panel for a tripped switch before calling.
Ask about current after-hours rates when you call +1-866-805-8548.
More involved repairs, like a coil replacement or a refrigerant leak repair, take longer and the tech will give you a realistic estimate before starting.
Let dispatch know ahead of time if access will be handled differently than a standard homeowner visit.
Our technicians are familiar with both, which means less time spent figuring out your specific setup and more time actually fixing the problem.
If you manage several units or a shared system across a O Fallon property, ask about setting up a standing service account so every request gets handled under one consistent agreement.
Qualifying installations can be financed through options we'll walk you through during your in-home estimate, with terms explained clearly before you commit to anything. If a rebate or local incentive program applies to your O Fallon installation, our technicians will flag it during the estimate rather than leaving you to track it down after the fact.
We dispatch throughout O Fallon and the neighboring communities, keeping response times tight because our trucks stay close to home.
Property managers with multiple O Fallon addresses can consolidate everything under one account for simpler scheduling and consistent pricing across every location.
