What a real PM visit includes
On a rooftop unit or split system, a proper visit covers: coil condition and cleaning, filter replacement, belt condition and tension, electrical inspection — contactors, capacitors, wire terminations, amp draws against nameplate — refrigerant circuit performance, condensate drain clearing and treatment, economizer and damper operation, and a controls check against setpoints. Every unit gets its own written report, so you can see condition trending across visits.
The energy line nobody sees
A dirty condenser coil can add 15 to 25 percent to a unit's energy draw before anyone notices a comfort problem, because the unit compensates by running longer. Across a fleet of rooftop units, coil cleaning and correct charge are usually the fastest payback in the building. You never get a line item for energy you did not waste — but it is real money every month.
Small parts, big failures
Most catastrophic HVAC failures start as five-dollar problems. A weak capacitor stresses a compressor for months before the compressor dies. A slipping belt burns out a blower motor. A clogged drain trips a float switch — or floods a ceiling. PM exists to catch the cheap version of the failure, on a scheduled visit at scheduled rates, instead of the expensive version on an emergency call.
Cadence: what to do how often
For most commercial buildings in the Carolinas, quarterly visits fit equipment with belts, economizers, and heavy runtime; semi-annual (spring and fall) suits lighter-duty units. Kitchens, manufacturing, and anything with heavy filter loading may justify monthly filter service between full visits. The right cadence comes from the equipment list — which is exactly how we quote it.
What it costs
Our PM pricing is per unit and published: $200 for the first RTU or split system at a site, $149 for each additional, and $149 on every unit once a site has four or more. Contract customers also get 24/7 emergency response and the trip fee waived on covered equipment.
What preventative maintenance does not cover
A PM program is an inspection and cleaning program. It is not a repair contract, and the distinction matters when you compare proposals. On an SBS-NC program the visit price covers the labor on site, standard filters and belts, coil cleaning, and the report. The things it does not include are the same on every honest proposal:
- Repairs and parts found during the visit. A failing capacitor, contactor, or fan motor gets written up with a price. You approve it before it is replaced.
- Refrigerant beyond a minor adjustment. A unit that is low on charge has a leak. Finding and repairing it is a separate, priced job under EPA Section 608 rules.
- Ductwork, duct cleaning, and air balancing. These are separate trades and separate quotes.
- Controls reprogramming or building automation changes. Verifying that a thermostat or sequence works is PM. Rewriting the sequence is not.
- Code upgrades and equipment replacement. The PM report should tell you when a unit is approaching end of life so replacement can be budgeted, but the replacement itself is a capital project.
Rooftop fleets and central plants are different programs
A rooftop unit or a split system is a self-contained machine, so its PM is a repeatable checklist that scales across sites and prices per unit. A central plant is not. Chillers, boilers, cooling towers, and pumps are interdependent, cost far more per hour of downtime, and need annual tasks that have nothing in common with a rooftop visit: eddy-current tube testing, oil analysis, refrigerant analysis, burner tuning and combustion analysis, tower fill inspection, and water treatment coordination. That is why central plant maintenance is quoted per machine after a walk-through rather than off a per-unit rate.
What a good PM report shows
The report is the product. If you cannot read it and know the condition of every unit, you are paying for a filter change. A report worth paying for includes:
- One entry per unit, identified by your asset tag or a tag the contractor applied, with its location and nameplate data.
- Measured readings, not checkmarks: amp draws against nameplate, refrigerant pressures and superheat or subcooling, supply and return temperatures, static pressure where it matters.
- Photos of anything that was found, cleaned, or flagged.
- Filter sizes and belt numbers per unit, so a replacement does not require a second trip.
- A deficiency list sorted by urgency, each with a price, so you can approve, defer, or budget without another site visit.
- A fleet-level summary: units over fifteen years old, units with repeat findings, and anything that should move to the capital plan.
A seasonal checklist for the Carolinas
- Spring (March to April): condenser coil cleaning before pollen season peaks, refrigerant circuit checks, condensate drain clearing and float switch testing, economizer and damper operation, and a full electrical inspection before the first heat wave.
- Summer (June to July): filters, belts, condensate drains again, amp draws under full load, and a check of any unit that logged a fault or a comfort complaint since spring.
- Fall (September to October): heat exchanger inspection, gas valve and ignition testing, flue and combustion air verification, heat pump defrost cycle testing, and a last look at coils before winter.
- Winter (December to January): filters, belts, heating operation under load, freeze protection on any hydronic or make-up air equipment, and a review of the year's findings to set the next year's budget.
Quarterly programs land on this calendar naturally. Semi-annual programs combine spring with summer and fall with winter, which works for lighter-duty equipment and misses the mid-season drain and filter checks that keep kitchens and high-runtime sites out of trouble.
Sources & further reading
- ANSI/ASHRAE/ACCA Standard 180 — Standard Practice for Inspection and Maintenance of Commercial Building HVAC Systems (via DOE Better Buildings)
- U.S. DOE Federal Energy Management Program — Operations & Maintenance Best Practices Guide (Release 3.0)
- U.S. EPA — Stationary Refrigeration and Air Conditioning (Clean Air Act Section 608)