Troubleshooting / Chiller / cooling

Chiller / Cooling Troubleshooting

The most common chiller / cooling problems on the plant floor, with the likely causes and the fix for each. Part of the OEE Lab troubleshooting directory.

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Problems on this page:

Insufficient coolingHigh-pressure tripShort-cycling / low-flow alarmLow-pressure or freeze protection tripProcess temperature swingingWater or glycol leaks in the loopCoolant fouling the process equipmentCompressor or fan noise rising

Insufficient cooling

Hits OEE: Performance

Symptoms: Process runs hot, chiller cannot hold setpoint, downstream quality drifts.

Low refrigerant charge
Check for leaks; have a licensed tech recharge.
Fouled condenser
Clean condenser coils; clear airflow or check water side.
Low coolant flow
Check pump, strainer and valves; bleed air; clean filters.
Scaled/fouled evaporator
Descale/clean the evaporator; treat the water loop.

Prevention: Condenser cleaning, water treatment, flow and refrigerant checks.

High-pressure trip

Hits OEE: Availability

Symptoms: Chiller trips on high head pressure and shuts down.

Condenser fouling or blocked airflow
Clean the condenser; restore airflow/water flow.
Condenser fan failure
Replace the failed fan; check controls.
Overcharge or non-condensables
Have a tech correct the charge; purge non-condensables.

Prevention: Condenser maintenance, fan checks, correct charge.

Short-cycling / low-flow alarm

Hits OEE: Performance

Symptoms: Chiller starts and stops rapidly or trips on low flow.

Low flow / clogged strainer
Clean the strainer; check pump and valve line-up.
Air in the loop
Bleed air; check expansion/make-up.
Setpoint differential too tight
Widen the control differential within spec.

Prevention: Strainer cleaning, loop de-aeration, sensible differentials.

Low-pressure or freeze protection trip

Hits OEE: Availability

Symptoms: The chiller trips on low suction pressure or on its freeze protection, often at low load or on cold days.

Coolant flow through the evaporator too low
Check pumps, strainers and valves on the chilled side.
Glycol concentration too low for the set point
Test the glycol and correct it for the lowest temperature in use.
Low refrigerant charge
Have a qualified technician check for leaks and the charge.
Set point below what the system was designed for
Check the set point against the design.

Prevention: Glycol tested before the cold season.

Process temperature swinging

Hits OEE: Quality

Symptoms: The supply temperature to the process swings and product quality follows it.

Chiller capacity steps too coarse for the load
Check the capacity control and consider a buffer tank.
Too little water volume in the loop
Add buffer volume so the chiller does not short cycle.
Temperature sensor badly placed or drifting
Check the sensor position and calibrate it.
Three-way valves or bypasses set wrong
Check the valve settings at each user.

Prevention: Supply temperature trended at the process.

Water or glycol leaks in the loop

Hits OEE: Availability

Symptoms: The loop pressure falls, the make-up runs often, wet spots appear under pipes or machines.

Hoses or fittings at the machines failing
Replace aged hoses and tighten fittings.
Pump seal leaking
Replace the pump seal.
Corrosion in the pipework
Check the water treatment and inspect the pipes.
Relief valve lifting
Check the loop pressure and the expansion vessel.

Prevention: Make-up water use recorded so leaks show early.

Coolant fouling the process equipment

Hits OEE: Quality

Symptoms: Moulds, jackets or heat exchangers on the process lose cooling while the chiller itself looks fine.

Scale or biofilm in the loop
Treat the water and clean the affected equipment.
No filtration in the loop
Fit a side-stream or main loop filter.
Open tanks letting dirt in
Cover tanks or move to a sealed cooling circuit.

Prevention: Water treatment readings logged.

Compressor or fan noise rising

Hits OEE: Availability

Symptoms: New rattles, knocking or vibration from the compressor or the condenser fans.

Fan blade damaged or loose
Check and tighten or replace the blade.
Fan motor bearing wear
Replace the bearings or motor.
Compressor wear
Have a technician check the compressor.
Loose panels or mountings
Tighten panels and replace failed anti-vibration mounts.

Prevention: Noise and vibration checked on the route.

Guidance only. Always follow lockout/tagout and your site's safe-work procedures, and verify against OEM manuals before acting.

Related equipment guides: cooling tower · refrigeration compressor · blast freezer · air handling unit · mould temperature controller · evaporative condenser · UPS system · enrober · cooling tunnel · carbonator · induction hardening machine · brazing furnace · laser welding machine · anodising line · cable extrusion line · industrial dehumidifier · temperature sensor · chocolate tempering machine · flake ice machine · fermentation tank · two roll mill · calender · pipe extrusion line

Stop the same fault coming back

Recurring chiller / cooling stops usually trace to a cause you cannot see by hand. The partner we recommend is Fabrico: it tracks OEE and downtime live from PLCs, IoT sensors or AI cameras; where cameras are fitted, the video of a stop sits next to its machine data so the cause can be reviewed; and a technician opens the work order from the stop in the same system. Data is hosted in the AWS EU region, and Fabrico and the company behind it hold ISO/IEC 27001, ISO/IEC 20000-1 and ISO 9001.

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Related tools: full troubleshooting directory · OEE calculator · downtime cost · MTBF / MTTR · glossary

Methods that cut recurring stops: the six big losses · root cause analysis · preventive vs predictive maintenance · TPM · SMED & changeover