HVAC Maintenance Checklist

Open the PM work order in the CMMS (Fiix, eMaint, Limble, MaintainX) and review the prior visit's notes — recurring issues, deferred items, and any open follow-ups from the last quarter. Note the unit tag, model, and refrigerant type before walking out to the equipment.

Follow the equipment-specific LOTO procedure per 29 CFR 1910.147 — disconnect at the unit, apply your personal lock and tag, and verify zero energy by attempting a start. A skipped LOTO during blower or burner service is the OSHA Top-10 finding most likely to end careers.

Pull replacement filters at the MERV rating specified for this unit, the belt size from the nameplate, and the refrigerant-specific gauge manifold (R-410A vs. R-22 vs. R-32 — never share manifolds across refrigerants).

Match the MERV rating on the spec sheet — over-spec'ing the filter restricts airflow and trips high static alarms on the BAS. Note arrow direction and seat the filter against the gasket, not just into the rack.

Remove buildup from the blower wheel blades — a fingernail of dust per blade drops CFM measurably and unbalances the wheel. Inspect the housing for corrosion at the drain pan seam.

Use a tension gauge to the belt manufacturer's spec — finger-deflection is not a measurement. Lay a straightedge across both sheaves to verify alignment; misalignment shortens belt life by half and burns bearings.

Torque each lug to the manufacturer's spec on the inside of the panel door. Look for pitting on the contactor points — pitted contacts cause single-phasing and burn motors. Replace the contactor if points are pitted past a credit-card thickness.

Force a setpoint change at the BAS or stat and verify the unit responds — heating call, cooling call, fan-only. Note any drift between commanded and measured temperature greater than 2°F.

Walk the suction and liquid lines from the compressor to the indoor coil. Oil staining at flare fittings, brazed joints, or schrader cores is the field signature of a slow leak — confirm with an electronic detector or bubble solution before charging.

Connect the manifold and let pressures stabilize before reading. Record both readings against the saturation chart for the unit's refrigerant; pressures outside the manufacturer's envelope point to undercharge, overcharge, or a metering-device fault before they cause a compressor failure.

Based on the line inspection and pressure readings, declare whether a leak is present. EPA Section 608 leak-rate thresholds for commercial refrigeration begin at 35% annual leak rate — appliances over the threshold trigger mandatory repair within 30 days.

EPA Section 608 requires a certified technician to recover refrigerant before opening the system, and to log recovered/added quantities in the unit's service record. Schedule the leak repair within the regulatory window and notify the maintenance lead before any topping-off.

Use coil cleaner rated for the fin material — aluminum-fin condensers reject acidic cleaners, copper coils tolerate them. Rinse from the inside out so debris exits the way it entered.

Measure superheat at the suction line near the TXV bulb; compare to the manufacturer's target (typically 8–12°F). Persistent high superheat with normal pressures usually means a sticking valve or a lost bulb charge, not a refrigerant problem.

Check transverse joints and longitudinal seams for separation, mastic failure, or open screws. Leaks at the supply trunk near the unit are responsible for the bulk of measured duct losses — fix these before chasing branch leaks.

Stroke each accessible damper through full travel and confirm the actuator returns to commanded position. Stuck fire dampers are an NFPA 80 finding at the next fire-marshal inspection; document any that won't reset.

Take a hood reading at two or three diffusers and compare against the balance report. Drops of more than 10% from the commissioning baseline usually trace back to filter loading, a slipping belt, or a closed damper.

Use a borescope on each cell — daylight inspection misses hairline cracks that vent CO into the supply air. A cracked exchanger is a life-safety condition: the unit gets red-tagged immediately, no exceptions for production schedule.

Lock the unit out of service, apply a red Do-Not-Operate tag, and call the maintenance lead before leaving the roof. A cracked exchanger that runs another shift is how facility CO incidents become OSHA recordables.

Cycle the heat call and watch the ignition sequence: pre-purge, igniter glow or spark, gas valve open, flame proven, blower on. Measure the flame-rectification microamps against the board's minimum — a weak signal predicts nuisance lockouts on the coldest morning.

Use a calibrated combustion analyzer at the flue. Record O2, CO2, CO, and stack temperature; compare against the burner manufacturer's targets. CO above 100 ppm air-free is a stop-and-fix condition, not a tweak-the-air-shutter condition.

Walk the panel and confirm covers are reinstalled and screws torqued before pulling locks. Restore power, watch the first start cycle, and listen for unusual bearing or contactor noise before leaving the equipment.

Upload field photos of the filter change, coil condition, and combustion-analyzer readout. Attach the technician signature to close the CMMS work order; the maintenance lead reviews the sign-off and any flagged follow-ups before the WO closes for the quarter.