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Commercial HVAC Services
Serving Modesto, Manteca and Riverbank in the Central Valley
Commercial HVAC Built for Modesto's Long Summers
A Modesto summer asks a lot of any building's commercial HVAC system. Rooftop units run from opening to close for months, and every hour wears on motors, belts and coils. When one part gives out, the whole space feels it, from the sales floor to the back office.
Catching that worn part before it shuts you down is the work we do. Dycus Heating and Air Conditioning, a family-owned commercial HVAC contractor in Modesto, has served businesses across the Central Valley since 2001. We work on everything from rooftop units and walk-in coolers to chillers and VRF systems.
365Days Availability
100%Local Technicians
25Years of Experience
Commercial HVAC Services From Repair to New Construction
As a full-service commercial HVAC company in Modesto, we split the work into six services, each with its own page. Start with the one that sounds like your building today.
Commercial HVAC Repair
When the commercial air conditioning quits on a hot afternoon, the building heats up within the hour. Every commercial HVAC repair starts with testing the electrical parts, refrigerant level and airflow. Once the failed part turns up, we walk you through it in plain words.
Commercial HVAC Installation & Replacement
A system that needs a repair every season can cost more to keep than to replace. When it's time, our commercial HVAC installation and replacement crew takes over. We size new commercial heating and cooling gear to the building's size and hours, not the old nameplate.
Commercial HVAC Maintenance
Most commercial breakdowns start small, as a dirty coil, a slipping belt or a worn contactor, the switch that starts the compressor. Regular commercial HVAC maintenance catches those early, long before they turn into a closed afternoon.
Light Commercial HVAC
Small offices, shops and restaurants usually run split systems or smaller packaged units. They need a contractor who prices light commercial HVAC work to that size. It's still a business that has to open on time, and we treat it like one.
New Construction HVAC
The easiest time to plan HVAC is before the framing goes up. On new construction HVAC projects, we work with builders and owners on equipment, duct design and zoning while a change still costs a pencil line.
Commercial VRF Systems
VRF heats and cools many zones from one outdoor unit, and every zone keeps its own temperature. Commercial VRF systems suit offices and schools where rooms fight over a single thermostat.
90 daysDays a year that reach 90°F or hotter in Modesto, per NOAA's 1991 to 2020 climate normals.
17.9 daysDays a year Modesto reaches 100°F or hotter, per NOAA's 1991 to 2020 climate normals.
About 40%Share of our work that's light commercial, so business HVAC is everyday work here.
4 visitsA year on our commercial maintenance agreements, one each quarter.
Commercial Equipment We Repair, Replace and Maintain
Commercial heating and air conditioning rarely comes down to one machine. A restaurant needs its rooftop unit, walk-in cooler and kitchen ventilation working at the same time, so we work across all of it.
Rooftop Units
Packaged rooftop units put every part of the system in a single box on the roof, and they're the most common setup on low-rise shops and offices. We service the major brands, Johnson Controls commercial units included, from failed motors and belts to dirty outdoor coils.
Commercial Refrigeration
Walk-in coolers keep food and stock at a safe temperature. A failing compressor or fan shows up as a slowly rising box temperature. We trace it to the part before your stock is at risk.
Chillers and Cooling Towers
Larger buildings move heat with chilled water. We service the chiller that cools the water and the cooling tower that sheds the heat outdoors. Both sides of that loop have to stay in balance.
Ventilation Rooms and Blowers
Fresh air and exhaust matter as much as cooling in kitchens, offices and classrooms. We service the blowers and motors that move that air, plus the dampers inside the ducts that steer it, so every room gets its share.
Water Pumps and Heat Exchangers
Hydronic systems, the kind that heat or cool with water, rely on pumps to move it and heat exchangers to pass heat between loops. We test both, because one weak pump can leave an entire floor short on heating or cooling.
Not sure which of these runs your building? Tell us what kind of business you operate, and we'll know where to look. A restaurant, a school and a rental property each lean on different equipment, so we've laid out the work we do for each industry.
Commercial Pricing Starts With a $169 Visit
What does commercial HVAC repair cost in Modesto? It starts with a $169 diagnostic. You're paying for the testing that finds the fault. That fee stays separate from the repair price, so the diagnosis stands on its own.
Every commercial job after that is priced by hand. A software price book can't see your roof access, duct age or zone count, so we quote the building in front of us.
Nothing starts until you approve the number. If replacing makes more sense, you'll see that price too.
Repair, Replace or Maintain Your Rooftop Unit
Advice Based on Your Unit's Condition
A twelve-year-old rooftop unit with one failed motor gets a repair quote. A unit on its third compressor gets a straight talk about replacing it. We lay out what each path involves and let you choose the one that fits your budget and your building.
| Repair | Replacement | Maintenance Agreement | |
|---|---|---|---|
| When it fits | One part failed on a system with good years left | Repairs come every season, or parts are hard to find | The system runs well and you want it to stay that way |
| What happens | We find the cause, replace the part and test the system | We size new equipment to the building and install it | A technician checks and cleans your equipment on a set schedule |
| What you get | The same system, running again | New equipment built for how your building runs | 15% off repairs as a member |
Why Businesses Hire Our Commercial HVAC Team
Trained by a Master Technician Who Teaches
Certified on Daikin VRV Systems
VRF is a specialty. Getting the piping, controls and startup right takes training on the equipment itself. Our team holds Daikin VRV certification, which is Daikin's own training for its VRF systems. A multi-zone office or school gets a crew that knows the equipment.
Owner Wrote an HVAC Curriculum
Our owner, David Dycus, started in the trade at 17. Later he earned teaching credentials, wrote an HVAC curriculum and taught apprentices for four and a half years. He also trained the manager who leads our install crews, so your building gets the standard he teaches.
Instructor-Trained Service Manager
The manager who runs our service team is trained at the instructor level. When your rooftop unit acts up, the technician who shows up answers to someone who can teach the work as well as schedule it.
What to Expect Once You Call Us
Whether it's one failed unit or a new building, the path looks the same.
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Tell us the symptoms
Call Monday through Friday between 7 AM and 5:30 PM. Our family-run office will ask about the symptoms, the equipment and how to reach it, then set the visit.
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A technician finds the cause
Your technician tests the equipment and traces the problem to the part. For a new system, this is the site visit where we measure every zone and ask when you open and close.
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Compare your options and costs
We walk you through each workable option and what it costs, then you decide which way to go.
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We finish and test
We complete the repair or installation, then run the system and check that every zone holds temperature before we leave the site.
Book a Commercial Service Call Today
Weekday Visits Often Happen Same Day
Same-day service is available on weekdays, so a building that stops cooling at lunch can often be running again before close. Call early, describe the equipment and the symptoms, and we'll send a technician with the right parts on the truck.
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Weekend On-Call Until 9 PM
Weekend trouble still gets an answer. Our on-call line picks up Saturday and Sunday until 9 PM, and calls after that are held for the morning.
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Have These Details Ready
The equipment brand and model number, where the unit sits, how to get on the roof, and what changed before it stopped. Those answers help us get it right the first time.
Commercial HVAC Across Stanislaus and San Joaquin Counties
Our commercial HVAC technicians look after businesses in every town listed below. A strip-mall restaurant in Ceres and a warehouse office in Riverbank get the same crew and the same checks. Towns farther than about 20 miles from Modesto carry an out-of-area fee, and the office mentions it when you book.
What Customers Say Once We're Done
Each quote below comes word for word from our Google profile, where we hold a 4.9-star rating.
"Dycus has always come out quickly and worked diligently each time to ensure the unit was working as it should and that I was happy with the result. Being a small business owner myself, service after the sale is paramount and Dycus excels in this area."
Paul G., Google review
"He took the time to explain things and I thoroughly enjoyed his proactive demeanor."
Gigi B., Google review
"They are responsive, friendly and honest."
Cheri N., Google review
Commercial Projects From Our Case Studies
Del Rio Country Club
A clubhouse VRF system. View the case study →
Commercial HVAC Questions From Business Owners
How long does a commercial HVAC system last?
Most rooftop units last about 15 to 20 years, and chillers often run longer with good care. Long summers, long operating hours and skipped service shorten that range. Regular maintenance helps a unit reach the high end and warns you early enough to budget for replacement.
How is commercial HVAC different from residential?
Commercial systems are bigger, often sit on the roof and serve many zones at once. Most run on three-phase power, the heavier electrical service businesses use, and they work longer hours than a home system. They also have to meet ventilation and energy code rules that home systems don't.
Do commercial HVAC replacements in California need permits?
Yes. A commercial replacement in California needs a permit from the local building department, and the job ends with a final inspection. The state's Title 24 energy code also requires the new equipment to pass acceptance tests before that inspection. Those tests prove the system works as designed.
What temperature should a commercial building be kept at?
OSHA's indoor air quality guidance recommends 68 to 76°F at work, with humidity between 20 and 60 percent. It's a guideline, not a rule. On a Modesto summer day, stay near the top of that range while you're open. After close, set it higher so the system can rest.
What refrigerant do new commercial HVAC units use?
R-454B and R-32 are now the refrigerants in most new packaged and split systems. EPA rules began moving new equipment off R-410A in 2025. Existing R-410A systems can still be repaired and recharged, so a unit that runs well doesn't need replacing over the change.