HVAC Maintenance Checklist by Equipment Type | Chiller, AHU, RTU, VRF
By Riley Quinn on February 6, 2026
Your technician just finished a "routine HVAC inspection." Took 20 minutes. Checked the filter, glanced at the thermostat, signed the work order. Done. Except the chiller's oil level wasn't checked. The AHU's belt tension wasn't measured. The RTU's condensate drain—the one that flooded the ceiling tiles last August—wasn't even looked at. Different equipment types have different components, different failure modes, and need different checklists. The facilities running at 95%+ uptime figured this out—and so should you.
78
Individual PM tasks on a typical commercial chiller
14+yr
Lifespan of a well-maintained RTU vs 9 years without PM
10-46%
Airflow reduction from dirty AHU coils alone
A single generic "HVAC inspection" form is like giving a surgeon the same pre-op checklist for every procedure. Facilities that switch to equipment-specific digital checklists eliminate missed tasks, improve consistency across technicians, and build an audit trail that proves compliance.
Chiller Maintenance Checklist
Chillers are the most expensive and complex HVAC asset in most facilities. Click any task below to see why it matters and how to perform it correctly.
Chiller
Quarterly + Annual
Dark or milky oil indicates moisture or refrigerant contamination that accelerates compressor wear. Check through the sight glass and sample for acid test. Replace every 2-3 years or when acid levels exceed thresholds.
Abnormal pressures indicate refrigerant charge problems, airflow restrictions, or internal wear. A 10% deviation from baseline warrants investigation. Record and trend values quarterly.
Scale buildup of just 1/32" reduces efficiency by ~10%. Monitor approach temperatures—a 1°F increase in condenser approach raises energy consumption 2-3%. Clean chemically or mechanically when values rise.
Federal EPA Section 608 requires leak inspections for equipment with 50+ lbs of refrigerant. With the R-410A phase-out, replacement costs are rising sharply. Use electronic leak detectors at all joints and service valves.
High/low pressure cutouts, flow switches, and thermistors are your last defense against catastrophic compressor damage. Simulate each fault condition to verify response—don't just visually inspect. Confirm BMS alarm routing works.
Click any task to see why it matters
AHU Maintenance Checklist
Air Handling Unit
Monthly + Quarterly
Clogged filters are the #1 cause of reduced AHU performance—increasing fan energy consumption 10-15% and forcing contaminants past filter media. Replace when differential reaches 0.5-1.0" W.C.
Worn belts slip, reducing airflow. Check deflection (max 1/64" per inch of span). Motor amps exceeding nameplate FLA by 10%+ indicates mechanical overload. Measure all three phases; imbalance >2% suggests electrical supply issues.
Dirty coils reduce airflow 10-46% with 41-60% more fan energy consumed. Clean with low-pressure water inside out. Flush drain lines with compressed air to prevent overflow, ceiling damage, and mold growth.
Stuck dampers waste energy and cause comfort complaints. Sensors drifting 2-3°F force the system to chase wrong setpoints. Measured airflow should be within 10% of design CFM.
Click any task to see why it matters
RTU Maintenance Checklist
Rooftop Unit
Seasonal + Quarterly
Amp draw exceeding nameplate RLA by 10%+ signals bearing wear or high head pressure. Target superheat 10-15°F, subcooling 8-12°F. Low superheat risks liquid slugging the compressor.
Rooftop coils accumulate leaves, cottonwood seeds, and dust that increase energy consumption 10-30%. Clean inside-out. Check filter rack for bypass gaps >1/4" that allow unfiltered air to foul the evaporator.
RTU drains clog frequently from outdoor debris causing ceiling damage and mold below. Cabinet gaps allow rain into electrical components. Seal gaps with caulk and treat surface rust before it penetrates.
Simulate fault conditions for high-pressure cutout, low-pressure cutout, and freeze stat. Verify economizer dampers respond correctly to outdoor air temperature. Inspect contactors for pitting—cheap parts that prevent expensive compressor damage.
Inspect refrigerant piping for leaks and insulation damage
Clean all indoor unit filters and coils per zone
Verify controller communication across all units
Test simultaneous heating/cooling performance
Cooling Tower
Test water pH, conductivity, TDS—adjust chemical dosing
Sample and test for Legionella (ASHRAE 188)
Inspect fan blades, lubricate bearings, check gearbox oil
Clean basin, strainers, nozzles, and drift eliminators
Boiler
Inspect burner, test combustion efficiency (CO, CO2, O2)
Inspect heat exchanger for cracks and corrosion
Test high-limit switch, low-water cutoff, relief valve
Verify fuel supply, expansion tank, and system pressure
With six equipment types each requiring dedicated task lists, paper checklists become unmanageable. Organizations that build digital equipment-specific checklists typically standardize across all HVAC assets within 30 days.
PM Frequency Guide by Equipment Type
Recommended Inspection Frequency
Swipe to see full table
Equipment
Filters
Mechanical
Electrical
Deep Inspection
Chiller
Monthly
Quarterly
Semi-Annual
Annual
AHU
Monthly
Quarterly
Quarterly
Annual
RTU
Monthly
Seasonal
Semi-Annual
Annual
VRF
Quarterly
Quarterly
Semi-Annual
Annual
Cooling Tower
Weekly
Monthly
Quarterly
Semi-Annual
Boiler
Monthly
Monthly
Pre-Season
Annual
Get These Checklists Working—Digitally
OXmaint auto-assigns the right checklist to every PM work order so technicians always have the right tasks for the right asset—tracked, timestamped, and audit-ready.
Expert Review: What Makes Equipment-Specific Checklists Work
The facilities with the lowest unplanned downtime rates treat each equipment type as its own maintenance discipline. A chiller has 78 potential failure points. An RTU has 25. A cooling tower has water treatment requirements that apply to nothing else. When you force all of that into one generic form, critical tasks get skipped. Equipment-specific checklists with digital tracking are the difference between a PM program that works and one that just looks good on paper.
Specificity Drives Quality
"Inspect system" gets pencil-whipped. "Check compressor oil level and condition" gets actually done and documented.
Digital Creates Accountability
Paper checklists vanish. Digital ones create timestamped records that prove compliance and feed trend analysis.
Frequency Is Half the Battle
Cooling towers need weekly water checks. RTUs need seasonal inspections. Wrong intervals are as costly as missed tasks.
The shift from paper to CMMS-driven checklists is where most facilities see the biggest PM compliance improvement. Facilities ready to make this transition can explore equipment-specific digital checklists that integrate directly with their work order workflow.
Stop Using Paper Checklists That Disappear
Join maintenance teams using OXmaint to deliver the right checklist for every equipment type—with auto-scheduling, mobile completion, and full audit trails.
Why do I need separate HVAC maintenance checklists for each equipment type?
Each HVAC equipment type has fundamentally different components and failure modes. A chiller requires up to 78 PM tasks spanning compressors, heat exchangers, and refrigerant circuits. An AHU focuses on belt drives, filters, and coils with up to 59 tasks. A cooling tower demands Legionella testing that applies to nothing else. One generic checklist guarantees critical tasks get skipped.
How often should each HVAC equipment type be inspected?
Cooling towers need weekly water checks and monthly mechanical inspections. AHUs and chillers require monthly filter tasks with quarterly mechanical checks and annual deep inspections. RTUs need seasonal inspections with quarterly spot checks. Boilers need monthly checks during heating season and comprehensive pre-season inspections.
How does a CMMS improve HVAC checklist management?
A CMMS auto-attaches the correct equipment-specific checklist to every PM work order. Technicians complete tasks on a mobile device with timestamps and verification. The system tracks completion rates, flags overdue tasks, stores inspection history per asset, and provides audit-ready documentation for compliance.
What are the most commonly missed HVAC maintenance tasks?
Tasks requiring measurement rather than visual inspection: compressor amperage vs nameplate ratings, safety control testing, sensor calibration, condensate drain verification, and belt tension/alignment checks. These directly prevent failures but get skipped when checklists are too vague.
How do I standardize checklists across multiple facilities?
Build master checklists per equipment type based on manufacturer specs and industry standards, then customize frequency for local conditions. A CMMS lets you create templates at the organizational level and deploy across all sites—consistent standards with site-specific flexibility.
