Most offices, stores, restaurants and small warehouses on Long Island are heated and cooled by rooftop units (RTUs): packaged systems that sit on the roof and push conditioned air down through the ceiling. Because they're out of sight, they're often ignored until a hot July afternoon or a cold January morning when the space stops being comfortable. A regular maintenance schedule prevents most of those failures and keeps energy bills in check. Here's what a proper RTU maintenance program covers.
How often should rooftop units be serviced?
At a minimum, twice a year: a cooling-season visit in spring and a heating-season visit in fall. Buildings with heavy loads, such as restaurants, gyms, salons, medical offices or spaces running long hours, benefit from quarterly service. Filters clog faster, belts wear faster, and economizers drift out of adjustment in those buildings.
Long Island's coastal air also matters. Salt and humidity corrode condenser coils, electrical connections and cabinet panels faster than they would inland, especially on South Shore and North Shore buildings near the water.
Every visit: the core checklist
- Filters: replace them. Dirty filters are the most common cause of high bills, frozen coils and poor airflow.
- Belts and pulleys: check tension, alignment and wear; adjust or replace worn belts. A snapped blower belt shuts down airflow to the whole zone.
- Motors and bearings: check amperage, listen for bearing noise, and lubricate where the motor allows it.
- Electrical: inspect contactors, capacitors, wiring and disconnects, and tighten connections. Loose, corroded connections are a leading cause of failed compressors and fan motors.
- Condensate: clear and flush the drain pan and line. A blocked drain on a rooftop unit can mean a ceiling leak into your space.
- Thermostats and controls: verify schedules, setpoints and sensor readings. Wrong schedules quietly waste money every night and weekend.
- Cabinet and panels: confirm all panels are secured and gaskets are intact so the unit isn't pulling in unfiltered roof air.
Spring (cooling season) visit
- Clean the condenser coil. On a rooftop, it collects pollen, debris and, near the coast, salt.
- Inspect the evaporator coil and clean it if airflow or temperature split shows it's dirty.
- Check refrigerant pressures and temperatures. Low charge means a leak, which should be found and repaired, not just topped off.
- Test the compressor and condenser fan motors.
- Check the economizer (below).
Fall (heating season) visit
- Inspect burners, ignition and flame sensors on gas-fired units.
- Inspect the heat exchanger for cracks or corrosion and verify combustion venting is clear. A failed heat exchanger is a carbon monoxide risk.
- Test safety controls: high-limit switches, rollout switches and pressure switches.
- For heat pump RTUs, test the reversing valve and defrost operation.
- Check that the unit's curb and duct connections are sealed before cold weather.
The economizer: the part most buildings ignore
Many RTUs have an economizer, a set of dampers that bring in cool outdoor air for "free cooling" when the weather allows. When an economizer sticks open, the unit heats or cools outdoor air all day and your bills climb. When it sticks shut, the building gets stale air and the compressor runs more than it needs to. Economizers commonly fail because of seized dampers, broken linkages or bad sensors, and nobody notices because the space still feels roughly comfortable. Checking damper movement and sensor readings should be part of every maintenance plan.
Roof access and safety
Technicians need safe, unobstructed access to your roof: a working hatch or ladder, keys, and a clear path to every unit. Make sure your landlord or property manager knows when visits are scheduled. A missed visit because the roof hatch is locked delays maintenance into the peak season, when breakdowns are most likely.
Keep a log for every unit
Each RTU should have its own record: make, model, serial number, filter size, belt size, refrigerant type, and what was found and done on every visit. A log shows which units are aging out, supports budgeting for replacements, and gives you documentation for landlords, insurers and lease obligations.
Signs an RTU needs attention now
- One zone runs hot or cold while others are fine
- Water stains on ceiling tiles below a unit
- New rattling, squealing or grinding from the roof
- The unit runs constantly but can't hold the setpoint
- A sudden jump in the electric or gas bill
- Burning or musty smells from supply vents
K2 commercial maintenance plans
K2 Cooling & Heating offers two commercial plans built around this checklist. Commercial Baseline Care covers spring and fall tune-ups, priority commercial scheduling, belt and bearing service, condition reporting and 10% off repairs. Commercial Enterprise Care adds quarterly inspections, economizer checks on every visit, refrigerant leak sweeps and vibration checks, a dedicated senior commercial technician, no dispatch fees on service calls during business hours, and a full digital logbook for each unit. See commercial maintenance plans.
Need a maintenance plan for your building's rooftop units? Call K2 Cooling & Heating at (631) 414-7141 or see our commercial HVAC services.
Need a technician rather than a guide? See our commercial HVAC service, or read about HVAC repair in Deer Park, NY. K2 answers 24/7 at (631) 414-7141.
