Monthly Checklist Items:

• ☐ Filter inspection: Check filter condition — record pressure drop if manometer present; replace if pressure differential exceeds manufacturer specification or visible loading exceeds 50%. Record filter type, MERV rating, and replacement date.
• ☐ Condensate drain check: Verify condensate pan is draining — check for standing water, algae growth, or drain line restriction. Flush with water if drain pan contains standing water.
• ☐ Operational temperature check: Verify supply air temperature at nearest diffuser is within 2°F of setpoint. Record actual supply temp and return temp.
• ☐ Unusual sounds check: Listen for bearing rumble, belt squeal, refrigerant hissing, or any unusual operational sounds. Document and escalate any identified abnormal sounds.
• ☐ Controls status check: Verify thermostat or BAS setpoints are at scheduled settings. Verify no fault codes present on controller display.
• ☐ Cabinet integrity check: Verify all access panels are secured. Check for any visible refrigerant oil staining that may indicate a refrigerant leak.

Quarterly Additional Checklist Items:

• ☐ Evaporator coil visual inspection: Inspect evaporator coil for debris accumulation, frost patterns indicating airflow restriction or refrigerant issues, and any visible corrosion. Note condition and any coil cleaning needed.
• ☐ Condenser coil visual inspection: Inspect condenser coil for debris, fin damage, and obstructions to airflow. Note fin straightening or coil cleaning needed.
• ☐ Belt inspection (belt-drive systems): Check belt condition for cracks, glazing, or fraying. Check belt tension — deflection should be per manufacturer specification (typically ½” per foot of span). Record tension measurement. Replace if condition warrants.
• ☐ Blower wheel visual inspection: Inspect for debris accumulation, any sign of wobble or damage. Document condition.
• ☐ Electrical connection visual inspection: With power off and locked out — check all terminal connections for looseness, discoloration, or corrosion. Tighten any loose terminals. Note any connections requiring replacement.
• ☐ Refrigerant sight glass check (where accessible): Verify sight glass shows clear refrigerant without bubbles (at steady state) — bubbles indicate potential low charge.
• ☐ Condensate pan treatment: Add biocide tablet or pan treatment per manufacturer specification to prevent algae and biological growth in condensate pan.

Semi-Annual Additional Items:

• ☐ Coil cleaning (evaporator and condenser): Clean coils with appropriate coil cleaner per manufacturer recommendation. For condenser coils — flush with low-pressure water after cleaning agent dwell time. Record coil condition before and after cleaning.
• ☐ Refrigerant system check: Measure suction and discharge pressures with manifold gauges. Compare to manufacturer pressure-temperature specifications for ambient conditions. Record measurements. Escalate to qualified refrigeration technician if pressures indicate low charge or system issues. (Note: EPA Section 608 certification required to handle refrigerant.)
• ☐ Motor amperage check: Measure blower motor and condenser fan motor amp draw with clamp ammeter. Compare to nameplate FLA — escalate if actual amperage exceeds 90% of nameplate FLA under typical operating conditions.
• ☐ Lubrication — motor bearings (where specified): Lubricate motor bearings per manufacturer specification. Do not over-lubricate — excess grease damages bearings. Record lubricant type and quantity applied.
• ☐ Controls calibration check: Verify thermostat or sensor calibration by comparing control reading to calibrated reference thermometer. Record deviation. Recalibrate or schedule sensor replacement if deviation exceeds ±2°F.
• ☐ Economizer cycle check (where present): Verify economizer damper opens at appropriate outdoor conditions. Verify damper moves full range. Lubricate actuator if specified.

Annual Additional Items:

• ☐ Blower wheel cleaning: Remove and clean blower wheel of accumulated debris — even minor imbalance from dirt accumulation increases energy consumption and bearing wear.
• ☐ Heat exchanger inspection (gas systems): Inspect heat exchanger for cracks or corrosion that could allow combustion products into supply air. This is a safety-critical inspection — any cracks found require immediate system shutdown and repair before operation. Document inspection findings.
• ☐ Combustion analysis (gas systems): Measure CO₂, O₂, CO, and flue gas temperature. Compare to manufacturer specifications. Record measurements. Adjust burner as needed or escalate to qualified technician.
• ☐ Duct inspection (accessible sections): Inspect accessible ductwork for leaks, disconnections, insulation damage, and any signs of moisture or biological growth. Document and schedule repairs for any identified issues.
• ☐ Structural and mounting inspection: Inspect unit mounting, curb condition, and any structural supports. Check for vibration-related fastener loosening. Inspect roof penetrations for leaks around curb flashing.
• ☐ Major component condition assessment: Assess compressor, heat exchanger, and major components for condition indicators suggesting remaining useful life concerns. Document assessment for capital planning.