HVAC Company Serving St. Charles, MO

Need HVAC Service Today?

• Same-Day Appointments Available
• Emergency Service 24/7
• Licensed, NATE-Certified Technicians
• Family-Owned Since 1964
• 1,000+ Five-Star Google Reviews
• Financing Available

Call (636) 205-1631 or message us online to schedule an in-house HVAC evaluation today.

How Much Does HVAC Replacement Cost in St. Charles?

Most residential replacements in St. Charles fall into one of two ranges:

• AC Replacement with evaporator coil: approximately $5,500 to $9,200
• Complete HVAC system (furnace and AC): approximately $8,450 to $22,990 or more

What moves the cost within those ranges:

• Home square footage and the system tonnage required
• Ductwork condition and whether it needs sealing, modification, or replacement
• Standard versus high-efficiency variable-speed equipment
• Zoning for homes with multiple levels or additions
• Electrical or code updates required before installation
• Indoor air quality components added to the project
• Access challenges in historic construction or tight mechanical spaces

An AC replacement with evaporator coil typically runs approximately $5,500 to $9,200, while a complete HVAC system replacement ranges from $8,450 to $22,990 or more. Historic homes and newer construction in New Town can both push toward the higher end for different reasons. Our in-home evaluation gives you a number tied to the actual property. Request an estimate online or call (636) 205-1631.

HVAC Repair Costs in St. Charles: What to Expect

Before our technician arrives and pinpoints the exact issue, these ranges can help you get a sense of what a repair might run:

• Capacitor: $150 to $450
• Thermostat: $100 to $600
• Ignitor replacement: $180 to $350
• Flame sensor: $180 to $340
• Furnace capacitor: $150 to $350
• Blower motor: $500 to $1,400+
• Evaporator coil: $600 to $2,000
• Control board: $700 to $1,650
• Heat exchanger: $2,000 to $4,000
• Compressor-related failures: typically upwards of $1,000

Once our technician has diagnosed your system, you'll get a firm price along with an honest comparison to AC replacement or furnace replacement if that turns out to be the smarter long-term option. Need a diagnosis today? Call (636) 205-1631 and we'll get you scheduled.

HVAC Services Are Available in St. Charles

• AC Repair
• AC Installation
• AC Replacement
• Furnace Repair
• Furnace Installation
• Furnace Replacement
• Heat Pump Services
• Ductless Mini-Splits
• Indoor Air Quality
• HVAC Maintenance
• Emergency HVAC Service
• Boilers, geothermal systems, and commercial heating and cooling

Martin-Jetco Heating and Air Conditioning installs systems from all major HVAC brands, including York, Goodman, Daikin, Carrier, and Trane. Financing is available for qualifying projects.

Get Same-Day or Emergency HVAC Service in St. Charles

Martin-Jetco Heating and Air Conditioning offers emergency HVAC service around the clock, including evenings, weekends, and holidays.

For morning calls: Same-day service is the typical outcome. Our technicians are dispatched as quickly as scheduling allows, often arriving that afternoon.

For evening and weekend calls: Calls are answered and a technician dispatched without waiting until the next business day.

On every urgent visit:

• The technician diagnoses the problem on site before any work begins
• You receive a firm repair cost before authorizing anything
• Most repairs are completed during that same visit
• When parts need to be sourced, the repair is fully scheduled within 24 to 48 hours

Situations that should not wait:

• No heat when outdoor temperatures are dropping
• AC failed and interior temperatures are rising
• System running but delivering no airflow
• Burning smell or unusual sounds from the unit

System down right now? Call (636) 205-1631.

Lower the Cost of Your Next HVAC Upgrade: Financing & Rebate Options

Several programs can reduce what you pay out of pocket on a new system. Our technicians review all of them during the in-home evaluation:

• Financing for qualifying projects, turning the total into fixed monthly payments
• Spire utility rebates on eligible higher-efficiency equipment, filed by our team at installation
• Federal energy-efficiency tax credits on qualifying heat pumps and high-efficiency furnaces, with the credit amount depending on the equipment and tax year
• Seasonal promotions when available at the time of your estimate

You see equipment cost, payment options, and applicable savings together before making a decision.

Which St. Charles Neighborhood Are You In?

Different parts of St. Charles have genuinely different HVAC needs. Here is a quick guide to what our technicians typically find in each area:

• Historic Downtown, Frenchtown & the Commons. Pre-war brick homes, plaster walls, radiator heat, wood windows, and rooms that were never designed for central air. Historic preservation considerations affect what equipment can go where and how it can be installed. Our technicians specialize in retrofits, boiler service, and ductless mini-splits that preserve original construction while delivering modern comfort.
• New Town at St. Charles. Newer construction built around man-made lakes means above-average ambient humidity that standard AC systems often cannot manage. Oversized systems short-cycle without completing dehumidification runs. The fix is usually proper sizing, a whole-home dehumidifier, or a combination of both.
• Zumbehl Road & Elm Street Corridors. 1960s through 1980s brick ranches and split-levels where systems are frequently on their second replacement cycle and the original ductwork has never been reassessed. Air balancing, duct sealing, and return sizing are often as important as the equipment choice.
• Riverfront, Elm Point & Lower-Lying Areas. Proximity to the Missouri River floodplain creates basement moisture that operates independently of what the thermostat is doing upstairs. Dehumidification and moisture management, not just equipment replacement, are often the usual solutions here.

HVAC for Historic St. Charles Homes

One of the most common situations our technicians encounter in St. Charles is a homeowner in a historic home trying to cool rooms that were never designed for central air. Before recommending equipment, we evaluate whether ductwork can realistically be added or whether a ductless mini-split will preserve the home's original construction while providing better comfort.

The Frenchtown Historic District, Main Street, and the Commons Neighborhood contain some of the most architecturally significant residential properties in Missouri. Working in these homes is different from a standard HVAC call in several important ways:

• Plaster walls and original woodwork limit duct routing options. Running new ductwork through a Victorian brick home means opening walls, ceilings, and floors that may contain original plaster, lath, decorative millwork, or historic finishes. For many homeowners, that trade-off is not acceptable. Ductless mini-splits deliver room-by-room cooling and heating through a small penetration in the wall, leaving the original construction intact.
• Boiler and radiator systems are common and worth preserving. Many of St. Charles's oldest homes still heat efficiently with hot-water boilers and cast-iron radiators. Martin-Jetco Heating and Air Conditioning services, repairs, and replaces boiler systems, and evaluates whether maintaining the existing boiler, upgrading to a high-efficiency modern unit, or converting to forced air makes practical sense for each property.
• Historic preservation considerations affect equipment placement. Properties in the Frenchtown Historic District, the Commons Neighborhood Historic District, and other designated areas may require approval for certain exterior changes. Outdoor condenser unit placement, wall penetrations, and mechanical additions all factor into what is possible and how the project gets scoped.
• Windows, insulation, and infiltration affect load calculations. Original wood windows and older insulation in these homes create a different thermal profile than a standard suburban house. Our technicians perform load calculations that account for the actual heat gain and loss of the historic structure before sizing any equipment.
• Mini-splits as the modern retrofit solution. For rooms without ductwork access, ductless mini-splits have become the most practical retrofit option in St. Charles's historic core. They require no ductwork, preserve the visual character of historic interiors, and allow zone-by-zone temperature control that a single central system cannot provide.

Have a historic home in St. Charles that needs HVAC attention? Call (636) 205-1631 or schedule a visit.

Why New Town Homes Feel Humid Even with the AC Running

New Town at St. Charles was designed around man-made lakes and canals, and that water feature creates ambient humidity conditions that most cooling systems were not sized to manage. If your home feels cool but damp, the HVAC system is likely the reason, even if the thermostat is reading correctly.

• The oversized system problem. A unit that is too large for the home cools the air temperature quickly but shuts off before running long enough to pull moisture from the air. The thermostat is satisfied, the humidity is not. This is the most common cause of clammy air in New Town homes, and it is a sizing problem, not a system failure.
• Short-cycling explained. When a system starts and stops in frequent short cycles, it is not completing the dehumidification portion of the cooling cycle. The result is a house that registers the right temperature but feels sticky and uncomfortable. Replacing a short-cycling system with one that is correctly sized changes this immediately.
• Whole-home dehumidifiers. For New Town homes where the humidity issue is significant, adding a whole-home dehumidifier to the HVAC system allows active moisture control independent of whether the AC is running.
• Indoor air quality as part of the solution. Filtration, air scrubbers, and humidity control work together to address the full picture of indoor comfort in these homes, not just the temperature reading.
• Ductless mini-splits for specific zones. Rooms or areas of the home that consistently feel more humid than others may benefit from a dedicated mini-split that handles both cooling and dehumidification for that zone independently.

Why Split-Level Homes Never Feel Even

Split-level construction is one of the most common floor plans in the Zumbehl Road and Elm Street corridors, and it is also one of the most consistently uncomfortable. The reason is almost always distribution, not the equipment itself.

• Upper floors collect heat: Heat rises, and in a split-level home where the upper level is physically separated from the main level by a partial flight of stairs, warm air accumulates upstairs in summer regardless of the thermostat setting below.
• Supply ductwork was rarely balanced for the actual layout: Duct runs in 1960s and 1970s split-levels were sized to meet code, not to deliver equal comfort to each level. The main floor typically gets adequate supply air; the upper level gets whatever is left over.
• Return air sizing compounds the problem: An undersized return on the upper level cannot pull enough warm air back to the system, which means the upper floor stays warm and the main floor gets overcooled trying to compensate.
• Static pressure affects how hard the system has to work: When supply and return systems are unbalanced, the blower motor works against higher static pressure than it was designed for. This reduces airflow, strains the motor, and shortens equipment life.

In some split-levels, adding a zoning system with separate thermostats for each level resolves the problem without changing the ductwork. In others, the duct system needs to be rebalanced or modified. For upper levels with very limited duct supply, a ductless mini-split on that level can provide independent temperature control without the cost of a full duct renovation.

Our technicians measure airflow at every register and assess static pressure throughout the system before recommending any equipment change. The fix is often less expensive than a full replacement.

Commercial HVAC in St. Charles

St. Charles has a significant commercial presence that extends well beyond the historic Main Street corridor. Martin-Jetco Heating and Air Conditioning handles commercial HVAC for the full range of property types throughout the city:

• Historic commercial buildings on Main Street and Fifth Street where preservation requirements affect equipment placement and installation methods
• Hotels and hospitality properties near Ameristar Casino and the riverfront
• Restaurants and retail tenants throughout the Main Street corridor and the Streets of St. Charles
• Medical offices and clinical facilities near SSM Health St. Joseph Hospital on First Capitol Drive
• Office buildings and professional suites in Bogey Hills, North Duchesne Drive, and Fox Hill
• Industrial and warehouse properties along the Harvester Road corridor
• Manufacturing and distribution facilities near the Highway 94 and I-70 interchange

Commercial systems in St. Charles have their own set of uptime requirements, load profiles, and installation challenges. A restaurant on Main Street with kitchen exhaust and high occupancy loads has very different HVAC demands than a medical suite near the hospital, and both differ from a warehouse on Harvester Road. Our technicians assess each commercial property on its own terms.

Running a commercial property in St. Charles? Call (636) 205-1631 or contact us online to discuss your service needs.

Neighborhoods & Areas We Serve in St. Charles

Martin-Jetco Heating and Air Conditioning serves homeowners and businesses throughout St. Charles and the surrounding St. Charles County communities. The team works across the city's historic districts and established neighborhoods, including the Historic Downtown District, the Frenchtown Historic District, the Commons Neighborhood, New Town at St. Charles, and the Elm Point and riverfront areas along the Missouri River.

Service is available near the First Missouri State Capitol State Historic Site on Main Street, Frontier Park and the Katy Trail trailhead, Jean Baptiste Point DuSable Park, Blanchette Park and its Aquatic Center, Ameristar Casino, St. Joseph Health Center on First Capitol Drive, and Lindenwood University on South Kingshighway.

Families in the St. Charles City School District, Francis Howell School District, and Orchard Farm School District can reach Martin-Jetco Heating and Air Conditioning for HVAC service throughout the city. The team also serves private school families connected to Duchesne High School, Academy of the Sacred Heart, St. Charles Borromeo Catholic School, and St. Cletus Catholic School, as well as students and staff at St. Charles Community College.

Keep Your New HVAC System in Peak Condition

Yes. Our Home Comfort Agreement is built around a simple idea: catch problems while your system is still running, not after it quits on you.

Here's what's included:

• A visit before cooling season and another before heating season, each year
• A full safety and performance check every time, with any developing issues explained in plain terms
• 20% savings on parts and labor for repairs between visits
• No after-hours or weekend surcharge
• Bumped to the front of the line if something comes up unexpectedly
• A lower diagnostic fee during normal business hours
• Maintenance records on file, which cover most manufacturer warranty requirements

Given how much of St. Charles is working with historic homes, aging ductwork, or systems that have gone a while between tune-ups, a seasonal check-in tends to be the difference between a minor fix and a major one.

Why St. Charles Homeowners Call Martin-Jetco Heating and Air Conditioning

Martin-Jetco Heating and Air Conditioning has been family-owned since 1964, and we've spent that time working on homes across St. Charles County. If something needs a second look after a job, we come back and take care of it.

Every technician on our team holds NATE certification, the industry's leading independent credential. We install York, Goodman, Daikin, Carrier, and Trane, so our recommendations are shaped by what your home and budget need rather than one brand we're tied to.

A few things reflect that over the years: an A+ rating with the Better Business Bureau, six Angie's List Super Service Awards based on verified customer feedback, and York Dealer of the Year recognition on more than one occasion.

Frequently Asked Questions

What zip codes does Martin-Jetco Heating and Air Conditioning serve in St. Charles?

Martin-Jetco Heating and Air Conditioning serves all of St. Charles, including the 63301 and 63303 zip codes, along with neighboring St. Charles County communities.

My home is in the Frenchtown or Commons Historic District. Can you add or replace HVAC without damaging the original construction?

Yes. Our technicians are experienced with older construction and understand how to work within the constraints of plaster walls, original woodwork, and limited mechanical access. For homes without usable ductwork, ductless mini-splits are often the most practical option, delivering cooling room by room with minimal disruption to historic finishes. Where ductwork can be routed through less finished areas, our evaluation determines what is practical for the specific property.

I live in New Town at St. Charles. My house is newer but the humidity inside is always high. Is that an HVAC problem?

New Town was built around man-made lakes, and the higher water table affects ambient moisture levels in these homes. If the AC is short-cycling rather than running complete cooling cycles, it is not removing humidity effectively. An oversized system is a common cause. Our technicians check system sizing, runtime patterns, and airflow before recommending whether the fix is a ductless mini-split for a specific zone, a whole-home dehumidifier, or a system that was never correctly sized for the home's actual load.

How much does HVAC replacement cost in St. Charles?

• AC replacement with evaporator coil: approximately $5,500 to $9,200
• Complete system (furnace and AC): approximately $8,450 to $22,990 or more

Historic homes in 63301 and newer construction in New Town can both push toward the higher end for different reasons. Call (636) 205-1631 or request an estimate online for a number based on your specific property.

How much does AC repair typically cost in St. Charles?

• Minor repairs (capacitors, thermostats): $150 to $600
• Mid-range repairs (blower motors, evaporator coils): $500 to $2,000
• Major failures (compressors, control boards, heat exchangers): $700 to well over $1,000

Our technician confirms the exact cost after diagnosing the failure and compares it against AC replacement before recommending anything.

How much does furnace repair typically cost in St. Charles?

• Ignitor and flame sensor: $180 to $350
• Furnace capacitor: $150 to $350
• Blower motor: $500 to $1,400+
• Control board: $700 to $1,650
• Heat exchanger: $2,000 to $4,000

At the control board and heat exchanger level, our technicians compare repair against furnace replacement before pointing in either direction. Call (636) 205-1631 for a diagnostic visit.

My split-level home in 63303 has one level that stays warmer in summer. What causes that?

Split-level layouts with unbalanced duct runs are one of the more common complaints in the 63303 corridor. Supply air that was never properly distributed to the upper or lower level leaves one area consistently warmer regardless of the thermostat setting. Our technicians measure airflow at each register and map the duct layout to determine whether a duct correction, a zoning adjustment, or a dedicated ductless mini-split for that level is the right fix.

My furnace runs but the house stays cold. What is happening?

When a furnace cycles on and off without warming the house, it is almost certainly tripping a safety shutoff mid-cycle. Clogged filters are the most common trigger: restricted airflow causes the heat exchanger to overheat, which trips the limit switch and shuts the burners off while the fan keeps running. Replacing the filter and letting the system cool often clears it. If the problem continues, the limit switch may be failing, a control board fault may be interrupting the cycle, or the heat exchanger may have a crack. A cracked heat exchanger is a safety issue, so call (636) 205-1631 if a filter change does not resolve it.

Are heat pumps a practical option for St. Charles homes?

Modern heat pump models handle Missouri winters considerably better than older equipment. For homes with functional ductwork in good condition, a heat pump is worth comparing directly against a traditional furnace and AC. For historic homes without usable ductwork, a ductless mini-split heat pump is often the more practical path. Our evaluation covers both scenarios.

How often should HVAC systems in St. Charles be serviced?

A spring inspection before cooling season and a fall inspection before heating season covers most homes. In St. Charles, where the housing stock spans nearly two and a half centuries of construction from Frenchtown brick rowhouses to 2010s walkout subdivisions, the range of system types and ductwork conditions is wide. Consistent maintenance catches developing problems before they become failures, and documented HVAC maintenance keeps most manufacturer warranties valid.

Is financing available for HVAC work in St. Charles?

Yes. Financing is available for qualifying projects. Our evaluation also covers Spire rebates, applicable federal energy-efficiency tax credits, and any current seasonal promotions, so the complete cost picture is clear before you make a decision.

Get HVAC Help in St. Charles Today

Whether the system needs replacing, a comfort problem in a specific zone has gone unresolved, or something needs attention right now, Martin-Jetco Heating and Air Conditioning can help. Call (636) 205-1631 or schedule your evaluation online.