Common Screw Chiller Problems and How to Fix Them
Sep 30, 2026
Screw chillers are widely used in plastics processing, chemical production, food manufacturing, pharmaceutical facilities and other industrial applications. They are suitable for applications requiring relatively large cooling capacities and stable operation over long production cycles.
However, even a well-designed industrial screw chiller can develop problems after extended operation. High-pressure alarms, low-pressure faults, unstable water temperatures and compressor overheating are among the issues maintenance teams may encounter. Understanding the possible causes helps technicians identify the source of a problem instead of replacing components unnecessarily.
Quick Answer
The most common screw chiller problems include high-pressure faults, low-pressure faults, insufficient cooling capacity, abnormal compressor temperatures, water-flow problems and electrical failures. Common causes include poor heat transfer, incorrect refrigerant conditions, restricted water circulation, electrical instability and inadequate maintenance.
The recommended approach is to check the alarm history first, verify water flow and operating temperatures, inspect the condenser and evaporator, and then investigate the refrigeration and electrical systems. Refrigerant adjustments and compressor repairs should only be carried out by qualified technicians.
Key Takeaways
High-pressure faults often involve condenser heat rejection.
Low-pressure faults may result from refrigerant shortages, restricted flow or abnormal operating conditions.
Reduced cooling capacity does not automatically mean the compressor is failing.
Water quality and stable circulation have a direct effect on chiller performance.
Recording operating data before a shutdown can make troubleshooting more efficient.
1. High-Pressure Fault: Check Heat Rejection First
A high-pressure alarm occurs when the refrigerant condensing pressure exceeds the permitted operating range. For a water cooled screw chiller, possible causes include insufficient condenser-water flow, excessive cooling-water temperature, a malfunctioning cooling tower or scale buildup inside the condenser.
For an air cooled screw chiller, dirty condenser coils, blocked airflow, failed fans or hot air recirculation can create similar problems.
How to fix it: Check condenser cleanliness, water flow or fan operation, depending on the chiller type. For water-cooled units, also inspect cooling-tower performance and condenser-water temperature. If these conditions are normal, a qualified technician should investigate refrigerant charge and other refrigeration-system conditions.
Hengde Insight：When a screw chiller develops a high-pressure alarm, do not start by assuming that the refrigerant charge is incorrect. Ask where the heat is supposed to go and whether the condenser can transfer that heat away effectively. This question can prevent unnecessary refrigerant adjustments.
2. Low-Pressure Fault: Look Beyond Refrigerant Charge
Low-pressure protection may be triggered by insufficient refrigerant, a restricted filter-drier, an expansion valve problem, inadequate evaporator load or insufficient chilled-water flow. Very low water temperatures can also contribute to abnormal operating conditions if the system is not designed for them.
How to fix it: Check the chilled-water flow, inlet and outlet temperatures, evaporator condition and relevant refrigerant readings. Inspect for signs of refrigerant leakage before adding refrigerant. If a restriction or expansion valve fault is suspected, have a qualified refrigeration technician investigate it.
Adding refrigerant without identifying the underlying cause may temporarily change operating pressure without resolving the actual problem.
3. Insufficient Cooling Capacity
Sometimes a screw chiller continues running but cannot maintain the required process-water temperature. This can happen when the actual heat load exceeds the design capacity, water flow is insufficient, heat exchangers are fouled or the compressor capacity-control system is not operating correctly.
Production changes can also increase cooling demand. A chiller that worked well when a production line was first installed may struggle after additional equipment is connected.
How to fix it: Compare the current cooling load with the original design conditions. Measure water flow and temperature difference, inspect the heat exchangers and verify compressor loading. If production demand has increased significantly, the cooling system may require hydraulic modifications or additional capacity.
Hengde Insight：Before recommending a larger chiller, confirm whether the existing capacity is being used effectively. Poor flow distribution, fouled heat exchangers or incorrect control settings can make a correctly sized machine appear undersized.
4. Compressor Overheating or Frequent Trips
Compressor overheating and repeated overload trips should never be ignored. Potential causes include excessive operating pressure, inadequate lubrication, abnormal refrigerant conditions, high discharge temperature, voltage imbalance or mechanical wear.
How to fix it: Record the alarm code, compressor current, operating pressures and temperature readings. Check the power supply and relevant protection devices. Lubricating oil condition, oil level and oil-system operation should be inspected according to the compressor manufacturer's instructions.
Do not repeatedly reset the compressor and return the machine to service without identifying the reason for the trip. Persistent overheating or abnormal mechanical noise requires professional inspection.
5. Water-Flow Problems and Heat Exchanger Fouling
Insufficient water flow can reduce heat-transfer performance and trigger protective shutdowns. Common causes include clogged filters, partially closed valves, air trapped in the piping, pump problems or deposits inside the heat exchanger.
How to fix it: Check pump operation, water pressure, valves, filters and flow-switch status. Inspect water quality and arrange appropriate cleaning when scale or deposits are found. The cleaning method must be compatible with the heat exchanger materials and the manufacturer's recommendations.
Maintenance intervals should be based on water quality, operating hours and inspection results rather than following a fixed schedule regardless of actual conditions.
A Practical Troubleshooting Sequence
When a screw chiller stops unexpectedly, technicians can follow this sequence:
Record the alarm code and operating conditions before resetting the unit.
Verify incoming power, phase balance and electrical protection status.
Check chilled-water flow, pump operation and water temperatures.
Inspect condenser conditions and heat rejection.
Review refrigerant pressures and compressor operating data.
Inspect lubrication, capacity control and relevant protection devices.
Run the machine under normal conditions and confirm that the fault does not recur.
Electrical and refrigeration-system work should be performed by qualified personnel. Isolate power before electrical inspection, and never bypass safety protection to keep a machine running.
Hengde Screw Chiller Products and Company Information
Nanjing Hengde Electrical Equipment Co., Ltd. has manufactured industrial temperature-control equipment since 2010. Its product range includes air-cooled chillers, water-cooled chillers, screw chillers, scroll chillers, low-temperature chillers and mold temperature controllers.
For example, Hengde's HC-600WD water-cooled screw chiller has a nominal cooling capacity of 600 kW (200 HP), with two semi-hermetic screw compressors. This model illustrates the type of large-capacity cooling equipment used in demanding industrial applications. Actual performance depends on the specified operating conditions.
Hengde operates a 15,000 m² facility with more than 150 employees and provides customized cooling solutions based on cooling capacity, water temperature, ambient conditions, flow requirements, voltage and application needs. When selecting or troubleshooting a screw chiller, matching the system configuration to the actual process requirements is essential for reliable long-term operation.
FAQ
Why does my screw chiller keep showing a high-pressure alarm?
Common causes include poor condenser heat transfer, high cooling-water temperature, insufficient water flow or restricted airflow. Check the heat-rejection system before investigating refrigerant charge.
How often should a screw chiller be maintained?
Maintenance frequency depends on operating hours, water quality, environmental conditions and the manufacturer's recommendations. Regularly inspect filters, heat exchangers, electrical connections, operating pressures and compressor data.
When should a screw chiller compressor be replaced?
A compressor should not be replaced based on a single alarm. Confirm the fault through operating data, electrical tests, lubrication checks and professional mechanical diagnosis before deciding on replacement.
Conclusion
Most screw chiller problems become easier to diagnose when technicians follow a systematic process rather than immediately replacing components. Start with the alarm history, verify water circulation and heat rejection, and then investigate refrigeration, lubrication and electrical conditions. Consistent maintenance and accurate operating records can help reduce unexpected shutdowns, protect the compressor and extend the service life of an industrial screw chiller.
