The Commercial HVAC Maintenance Checklist (Quarterly + Annual)

A 5-ton rooftop unit fails on a 105-degree Saturday at 1:15 p.m. The store is a clothing retailer in a Washington shopping center, peak weekend traffic, and the indoor temperature climbs from 74 to 88 in under an hour. The manager closes the doors at 2:30. We get the call at 2:38. By the time a tech is on the roof at 4:15 (emergency rate, weekend dispatch), the compressor has thermally locked, the contactor is welded shut, and the fan motor bearings are dry. The repair runs $2,840. Lost Saturday revenue: $11,000 by the owner’s estimate. Replacement cost if the compressor had been weeks older: $9,500 for the unit, $14,000 installed.

A quarterly PM agreement on that store would have been around $1,200 a year. Over the seven years that unit had been running without one, the math is simple: $8,400 in PM versus a single afternoon that cost $13,840 in repair and lost sales, plus a compressor that’s now on borrowed time. We see this pattern every summer. The facility manager who got pushed into a bid-low building services contract three years ago, the franchisee who skipped the second visit because cash was tight, the property manager who inherited the building and never asked who was servicing the equipment. None of them planned to be in our queue at 3 p.m. on a Saturday.

If you manage a commercial building in Washington County, you need a written preventive maintenance schedule. Not a verbal agreement, not “we’ll call somebody when it breaks,” not the cheapest price on a one-page proposal. This is the commercial PM checklist we built from thirty-plus years of service tickets, broken down by interval, with the specific tasks a real technician should be doing on every visit.

Why commercial PM is different from residential

A residential 3-ton air conditioner runs maybe 1,200 hours a season. A commercial 10-ton RTU on a retail building runs 2,800 to 3,500 hours, year-round in some cases, with economizer and reheat cycles loading the equipment differently. Duty cycle alone explains why commercial PM intervals are tighter and why “once a year is enough” doesn’t survive contact with reality.

Equipment access is the next variable. Roof access requires a fall-protection plan, a documented ladder or hatch route, and on some properties a permit before a tech ever touches a unit. Splits in mechanical rooms, AHUs above hard ceilings, and VAV boxes tucked behind drywall all add labor that residential techs never deal with. PM scope and pricing reflect that.

Controls are the third. A residential thermostat is one wire, one node, one zone. Commercial buildings run building automation systems (BAS), DDC controllers, multi-stage economizer logic, and zone-by-zone setpoint scheduling. A PM that doesn’t include verifying control sequences misses half the equipment’s runtime behavior. The compressor can be perfectly healthy while the economizer dampers are stuck closed and the building is paying to mechanically cool air it could be free-cooling.

Code and health requirements close the gap. Restaurants run under NFPA 96 for grease ducts. Medical offices have pressure-relationship requirements between exam rooms, waiting rooms, and corridors. Grocery stores have refrigeration interfaces with the building HVAC that affect product temperatures. Schools and child-care have ventilation rates set by code. None of that is on a residential checklist.

Monthly tasks (facility staff or vendor)

Some tasks happen too often to wait for a tech. These are the things a competent maintenance staffer or a janitorial vendor with a brief checklist can handle, and they prevent more emergency calls than any other line item on this page.

• Visual filter check at every return; replace if visibly loaded, don’t wait for the calendar
• Confirm thermostat or BAS setpoints match the schedule, including weekend and holiday overrides
• Walk every drain pan and condensate line, looking for standing water, algae, or active drips
• Clear debris from condenser intakes and around outdoor units (cottonwood fluff, cardboard, pallets stacked too close)
• Listen at each unit for new noises like bearing whine, belt squeal, or contactor chatter
• Confirm economizer dampers are not stuck open during heating or stuck closed during cool weather
• Log indoor temperatures at problem zones if tenants have been complaining

Filters specifically: most commercial RTUs run 2-inch pleated filters in racks of two to six. Stock them on-site, label the rack with the size and quantity, and budget for monthly changes during dust season (March through October here) and quarterly the rest of the year.

Quarterly checklist (technician visit)

This is the visit a licensed HVAC technician runs, what we do on every quarterly stop on a commercial PM. If your current vendor’s checklist is shorter or vaguer than this, ask why.

1. Refrigerant pressures and superheat/subcooling on every circuit. Not just “checked refrigerant,” but actual numbers logged against ambient and indoor conditions. Superheat outside spec means an undercharge or expansion valve issue; subcooling outside spec means overcharge or restriction.
2. Electrical connections torqued. Every lug at the disconnect, contactor, capacitor, transformer, and control board. Loose connections heat up, oxidize, and eventually arc. We use calibrated torque drivers on terminals over 10 amps.
3. Contactor inspection for pitting and welding. Once contacts pit, the resistance climbs, the contactor overheats, and the next failure is the compressor it’s supposed to protect.
4. Capacitor microfarad reading under load. A 45+5 dual-run capacitor that reads 38+4 is failing. Replace before it strands the compressor.
5. Motor amp draw on the blower, condenser fan, and any auxiliary motors. Compare against nameplate FLA. Anything over 90% of FLA is a problem worth flagging.
6. Blower belt tension, alignment, and pulley wear. Belts stretch and slip; pulleys groove. Misaligned drives eat bearings. Belts and pulley sets are consumables, not warranty parts.
7. Condenser coil cleaning. Coil-cleaning solution, soft brush, low-pressure rinse from the inside out. Pressure washers ruin fins. A 15% loading on a condenser coil costs roughly 20% of cooling capacity.
8. Evaporator coil inspection. Pull the panel, look for biological growth, dust caking, and refrigerant staining. Note any items needing chemical cleaning at the annual deep-clean.
9. Drain line flush and trap inspection. Algae tablets monthly, full flush quarterly. A blocked condensate line in July dumps water onto a control board and shuts the unit down on a float switch, if there’s a float switch.
10. Thermostat or BAS calibration. Verify sensor accuracy against a calibrated thermometer. Drift of more than 2 degrees throws scheduling and economizer logic off.
11. BAS and controls check. Run through every operating mode: cooling, heating, economizer, dehumidification, ventilation override. Confirm the unit responds to commands as scheduled. Note any communication faults.
12. Economizer damper exercise and linkage inspection. Stuck dampers are the single most common BAS failure we find. Free-cooling savings disappear silently and the building pays for it for years.
13. Gas heat exchanger visual inspection (heating-season prep). Camera scope through the burner ports. Cracks, corrosion, or rust scaling get flagged for replacement or further evaluation.
14. Combustion analysis on gas-heat units. CO, CO2, O2, and stack temperature logged. CO over 100 ppm air-free is a service deficiency; over 400 ppm is a shutdown.
15. Safety controls verified. High-pressure switch, low-pressure switch, freeze stat, high-limit, rollout switch, flame sensor: every safety on the unit gets tested for response, not just visual.

A quarterly visit on a typical 10-ton RTU runs 90 minutes to two hours done correctly. If your current vendor is in and out in 30 minutes, half the items above are getting skipped.

Spring readiness (cooling season)

Spring is where the worst surprises hide. Equipment sat through winter, mice may have moved into ductwork or unit cabinets, and the first 95-degree day exposes anything that was marginal last October. The spring visit is heavier than a normal quarterly.

• Full condenser coil chemical cleaning (every other year minimum, annually for restaurants and dusty sites)
• Refrigerant charge verification with weighed-in confirmation if questionable
• Condensate system: full flush, P-trap reseal, float switch test, secondary drain pan inspection
• Sequence of operation testing: every cooling stage, every economizer position, every BAS-commanded mode
• Belt replacement on units past 18 months on the current belt
• Outdoor disconnect and rooftop GFCI test
• Evaporator coil photo log if any biological growth is present, scheduled for annual chemical clean

Fall readiness (heating season)

Fall PM in Southern Utah is shorter than what northern climates require, but we don’t skip it. Gas heat sees less runtime here, but a heat exchanger crack still puts CO into a building, and a flame sensor that’s been sitting all summer can be reluctant to start when the first cold morning hits.

• Heat exchanger camera inspection on every gas-fired unit
• Manifold gas pressure measured and documented (high fire and low fire on two-stage units)
• Ignition system test: hot surface igniter resistance, spark gap on direct-spark systems
• Flame sensor cleaning with steel wool and microamp draw verification
• Combustion analysis with calibrated CO meter, results documented in the report
• Limit switch and rollout switch tested by simulation
• Inducer motor amp draw and bearing condition
• Condensate trap on high-efficiency units flushed, neutralizer media checked

A startup CO test the first time a furnace fires for the season catches problems before tenants complain. We’ve found two cracked heat exchangers on October startups in the last five years that would have run all winter undetected.

Annual deep-clean and inspections

Once a year, beyond the quarterly scope, equipment needs work that takes longer than a normal visit and may require a tenant coordination window.

Coil chemical cleaning. Exterior condenser coils every year on dusty sites and restaurants, every two years elsewhere. Evaporator coils when the photo log shows enough biological growth to affect airflow or odor.

Blower wheel cleaning. Pull the wheel, hand clean the blades. A loaded blower wheel can lose 20% of CFM without any obvious symptom. Most are filthy by year three if they’ve never been pulled.

Duct inspection. Visual on accessible runs, camera on hard-to-reach sections. Look for separated joints, sagging flex, and amateur tenant-improvement work that punctures sealed ductwork.

Fire and smoke damper testing where applicable. Required by code on a one- or four-year cycle depending on jurisdiction. Document position, fusible link condition, and actuator function.

Indoor air quality verification. Total particulate, CO2 at peak occupancy, humidity profile, and ventilation rate calculation against ASHRAE 62.1 if the building’s design called for it. Our indoor air quality services cover testing, filtration upgrades, and UV-C installation when a building needs it.

Code-driven items unique to certain businesses

Generic PM doesn’t cover what specialized operations actually need. The following items are not optional.

Restaurants. NFPA 96 grease duct cleaning at intervals tied to cooking volume: quarterly for high-volume, semi-annual for moderate-volume, annual for low-volume, monthly for solid-fuel cooking. Hood filter cleaning weekly by staff. Makeup air unit sized correctly to the exhaust hood. We’ve found half a dozen Washington County restaurants running negative pressure because the MAU was undersized or off; that pulls combustion gases backward and creates real CO risk. Walk-in cooler and freezer condensers cleaned and inspected at the same intervals as the HVAC.

Medical offices and clinics. Pressure relationships verified annually: exam rooms slightly negative to corridors, waiting rooms positive, sterile storage positive, soiled-utility negative. HEPA filter changeouts on schedule with documented serial numbers. Filtration upgrade audits when CDC or local guidance shifts. AHU inspection scope expanded to include any biological controls, UV lamps, and humidifier maintenance.

Grocery and convenience stores. Refrigeration condensers integrated with the rooftop equipment need coordinated cleaning. A dirty refrigeration condenser raises product temperatures before any HVAC tech notices a complaint. Display-case airflow alignment checked when HVAC supply is rebalanced. Heat reclaim systems where present need the same TXV and sensor checks as primary refrigeration.

Schools and daycare. Ventilation rate audits, CO2 logging during occupied hours, filtration to MERV 13 minimum where the equipment supports it. We work with administrators across Washington, St. George, and Springdale on summer-break PM windows.

What a good PM agreement actually includes

If you’re shopping a PM contract, the proposal should answer all of the following clearly. Vague language here is the first sign of a contract you’ll regret.

Visit frequency. The number of quarterly visits and the scope of each. Spring and fall should be heavier than the off-season visits.

Equipment list. Every unit covered, by tag, model, serial, and location. Not “all rooftop units,” but itemized.

Task checklist. The specific tasks per visit, written down, by equipment type. The list above is a reasonable template.

Included consumables. Typically air filters, belts, drain tablets, and basic refrigerant top-off allowances. Anything excluded should be itemized.

Priority dispatch. A defined response time during business hours and after hours. PM customers should be jumping the queue, period.

After-hours rate. A discount off the standard emergency rate. We typically discount 15 to 20% for agreement customers.

Documented reports. Left after every visit, electronic copy filed. Refrigerant pressures, electrical readings, deficiencies, photos.

Annual review. A sit-down or call to walk through deficiencies, capital planning, and equipment near end of life.

Red flags in a PM proposal

What you don’t want to see in a bid:

• Vague scope. “Inspect equipment” is not a task. If the proposal can’t tell you what’s being inspected and how, the work isn’t being done.
• No equipment list. A flat per-month price with no equipment tag list means change orders later and disagreements about what’s covered.
• No checklist deliverable. If reports aren’t promised in writing, you’ll never know what got skipped.
• No priority dispatch tier. A PM agreement that doesn’t put you ahead of one-time customers in July is paying for paperwork only.
• Subcontracted everything. Some property-services companies broker the HVAC work to whoever is cheapest that month. You want a vendor who owns the relationship and the equipment knowledge.
• Lowball pricing. A real quarterly visit is 90 minutes to two hours per unit by a qualified tech. The math doesn’t work below a certain price, and the work won’t match the proposal.

If you’ve already got a PM in place and any of those flags are showing, it’s worth getting a competing quote, not necessarily to switch, but to know what you’re paying for.

For facility managers and small business owners across Washington, St. George, Hurricane, Ivins, and Santa Clara, M&M Mechanical Inc. writes commercial PM agreements that document the scope above, leave you a report after every visit, and put your call at the front of the queue when something does go wrong. We’ve been on Washington County roofs since 1992. Call (435) 674-1275 or stop by 1430 Rio Virgin Drive in Washington. We’ll walk the equipment list and quote you a real PM, not a one-page handshake. In the meantime, the year-round residential maintenance schedule covers the home side of the same logic, and the signs your AC needs repair post is worth a read for the warning signs that show up in commercial equipment too.