Checklist
Chiller Maintenance Checklist
A chiller maintenance checklist covering refrigerant, compressors, condensers, evaporators, controls, and water treatment.
4 min readUpdated July 2026
Refrigerant System
- Check refrigerant charge: Verify superheat and subcooling are within manufacturer's range. Check sight glass for bubbles.
- Check for leaks: Use electronic leak detector on all flanges, valves, and joints. Repair any leaks found.
- Log operating pressures: Record suction and discharge pressures. Compare to baseline and manufacturer's data.
- Check refrigerant temperatures: Record saturated suction and condensing temperatures, and approach temperatures.
Compressor
- Check oil level: Verify compressor oil level is correct. Check oil colour — dark oil indicates contamination or overheating.
- Oil analysis: Sample oil for wear metals, acidity, and moisture. Compare to baseline.
- Check for unusual noise: Listen for knocking, grinding, or surging — indicates bearing, valve, or capacity control problems.
- Check motor current: Verify amperage is within nameplate rating and balanced across phases.
Condenser (Water-Cooled)
- Check condenser approach: Measure the difference between refrigerant condensing temperature and leaving cooling water temperature. An increase indicates fouling.
- Check cooling water flow: Verify cooling water flow rate and pressure drop are within design.
- Inspect tubes: During shutdown, inspect condenser tubes for scale and fouling. Clean if approach temperature has increased.
- Check water treatment: Verify condenser water treatment is maintained (scale inhibitor, biocide, corrosion inhibitor).
Evaporator
- Check chilled water temperature: Verify leaving chilled water temperature is at setpoint.
- Check approach temperature: Measure the difference between leaving chilled water and saturated suction temperature. An increase indicates fouling.
- Check chilled water flow: Verify flow rate and pressure drop are within design.
Controls
- Verify setpoints: Check all temperature and pressure setpoints are correct.
- Test safety interlocks: Test low-temperature, high-pressure, low-oil-pressure, and motor overload interlocks.
- Check capacity control: Verify the capacity control (unloading) is operating correctly across the load range.
- Calibrate sensors: Verify temperature and pressure sensors are reading correctly.
How CHI can help
Ask CHI about chiller maintenance and to help diagnose performance issues from your operating data. The CHI assistant can help you create custom checklists for your specific equipment, explain each inspection point, and flag items that need attention based on your equipment's condition.