Our O Fallon-based crews carry the parts and the know-how to get your air moving again today. Emergency dispatch available across O Fallon and the surrounding zip codes.
Our O Fallon dispatcher asks a few quick questions to gauge urgency and get you the fastest available window.
A licensed technician arrives, runs a full diagnostic, and explains exactly what's wrong in plain language.
Warranty details are explained clearly so you know exactly what's covered going forward.
Leonard HVAC was built by technicians who got tired of watching homeowners get oversold. 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. Every job we run is backed by full liability coverage and current state licensing, and we keep that documentation available on request for every job, routine or emergency.
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.
Too many homeowners in O Fallon have a story about a tech who showed up late, quoted one price, and charged another. That's the gap we built Leonard HVAC to close. We track arrival windows, callback rates, and repeat-issue complaints internally so problems get caught before they become patterns, 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. Our warranty and service history records stay attached to your address, so any future technician who visits already has the full picture.
We cover the full range of heating, cooling, and air quality work O Fallon properties actually need.
Breakdowns rarely happen at a convenient time, which is exactly why our emergency line runs 24 hours a day. Our O Fallon dispatch team moves emergency tickets to the front of the schedule 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.
If your unit is past its expected service life, running loud, or spiking your utility bill, a replacement conversation is worth having. 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.
Most installs in O Fallon are completed in a single day, and we walk you through the new thermostat and any app controls before we leave.
Commercial equipment operates differently than a residential unit, and it needs technicians who actually understand rooftop packages and multi-zone systems. Our commercial division services rooftop units and package systems across O Fallon, with service agreements built around your operating hours.
We understand that a commercial call isn't just about comfort, it's about keeping a business open.
Most emergency breakdowns start as a small, ignorable warning sign months earlier. 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.
Maintenance plan members in O Fallon get scheduling reminders automatically, so tune-ups don't fall through the cracks during a busy season.
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.
Emergency dispatch never comes with a hidden surcharge sprung on you after the fact.
Our office follows up after major repairs and installs to confirm everything is holding.
Most breakdowns don't happen without warning — they announce themselves for weeks before the system actually quits.
A healthy system runs with a consistent, low hum — banging, screeching, or grinding usually points to a loose part or failing motor.
This is one of the most common complaints we hear on service calls across O Fallon.
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.
You'll know the cost before a wrench touches your system.
Dispatchers give you a realistic arrival window instead of a vague "sometime today".
We don't consider a job finished until the system is actually performing correctly.
We run background checks because you're letting someone into your home.
You make the final call — we just make sure you have the full picture.
Replacement systems don't have to be paid in one lump sum.
We don't write these — our customers do.
"I called three other companies first and this was the only one that actually picked up. Fixed on the first visit and explained everything in terms I could actually understand."
"Scheduled a fall tune-up and they caught a cracked part before it became a real problem. Techs are always polite, always on time, and clean up after themselves."
"Had a full system replacement done and it was the smoothest home project I've had in years. New system is noticeably quieter and our energy bill actually dropped."
"Commercial dispatch was quick and the tech understood our system without needing to be walked through it. Kept our kitchen running through the weekend rush."
"The estimate matched the final invoice exactly, down to the dollar. My energy bill dropped noticeably the first month with the new system."
"Called at 11pm during a heat wave and honestly didn't expect anyone to pick up, let alone show up. Genuinely relieved to have found a crew that answers when it matters."
After thousands of service calls across O Fallon, a handful of causes show up again and again.
The shift between peak heating and peak cooling demand is exactly when older or neglected equipment tends to fail. Filters should be checked monthly during heavy-use seasons and replaced roughly every 60-90 days depending on your household and any pets.
Clearing debris, leaves, and overgrown landscaping away from an outdoor condenser unit gives it room to breathe and keeps it running efficiently. None of this replaces a professional tune-up, but it does reduce the wear that leads to premature breakdowns between visits.
Whether your O Fallon home has a traditional split system, a ductless mini-split, a heat pump, or a hybrid dual-fuel setup, our crews are equipped to diagnose and repair it. 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.
Every tech on our O Fallon roster goes through background checks, licensing verification, and ongoing manufacturer training.
Handles the majority of O Fallon installs and specializes in properly sizing equipment for older housing stock.
Keeps the emergency truck stocked based on what actually fails most often locally.
Works directly with O Fallon property managers to schedule around business hours.
Standard appointments are usually scheduled within 24-48 hours, while true emergencies jump the queue.
We explain the diagnostic fee upfront and provide a flat-rate repair quote once the issue is identified.
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.
We never push a replacement when a straightforward repair will genuinely solve the problem.
Plan members typically see fewer surprise breakdowns because small issues get caught during routine visits.
If you're unsure whether your address falls in our service area, a quick call to +1-866-805-8548 will confirm it.
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.
Most O Fallon homes benefit from two tune-ups a year — one before cooling season and one before heating season.
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.
Most standard repairs are completed in under two hours once the technician has diagnosed the issue and you've approved the quote.
For commercial accounts or rental properties, a designated point of contact or property manager can coordinate access instead.
Our technicians are familiar with both, which means less time spent figuring out your specific setup and more time actually fixing the problem.
We also work regularly with homeowners associations, property management companies, and multi-unit buildings throughout O Fallon.
We accept standard payment methods for repairs and smaller jobs, and we'll always tell you upfront what a given service is likely to cost so there's no last-minute scramble to figure out payment. 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.
If you're on the edge of our listed zip codes, it's still worth a call, since routes and coverage get adjusted as demand shifts.
