When an industrial chiller is running but the water temperature does not decrease, or the cooling capacity is significantly reduced, the problem can usually be identified from the following areas.

1. Common Causes

Possible Cause| Typical Symptoms| Inspection Method
Insufficient refrigerant or refrigerant leakage| Compressor runs, but water temperature does not drop sufficiently| Check high/low pressure, evaporator condition, and refrigerant leakage
Poor condenser heat dissipation| High discharge pressure and reduced cooling capacity| Clean the condenser and check the fan or cooling-water pump
Dirty or blocked evaporator| Poor heat exchange and abnormal temperature difference| Check the water circuit and clean the heat exchanger
Insufficient water flow| Unstable outlet-water temperature or water-flow alarm| Check the water pump, filter, and piping
Compressor malfunction| Abnormal noise, vibration, or operating current| Check compressor current and high/low pressure
Expansion valve problem| Abnormal refrigerant flow and poor evaporation| Check expansion-valve operation and superheat
Excessively high ambient temperature| Cooling performance decreases, especially in summer| Check installation environment and ventilation
Excessive cooling load| Cooling takes a very long time| Check whether the chiller capacity matches the actual load
Temperature sensor or controller failure| Displayed temperature differs from actual water temperature| Measure actual water temperature and inspect the sensor
Electrical/control system failure| Compressor cannot start or stops frequently| Check contactors, overload protection, relays, and control board

2. Recommended Troubleshooting Sequence

Step 1: Check the Water Circuit

First, make sure that:

• The water pump is operating normally.
• The water flow is sufficient.
• The water filter is not clogged.
• The pipes are not blocked or severely bent.
• The water tank has sufficient water.
• There are no obvious water leaks.

Step 2: Check Condenser Heat Dissipation

For an air-cooled chiller, check:

• Whether the condenser fins are dirty or blocked by dust.
• Whether the cooling fans are operating normally.
• Whether the fan rotation direction is correct.
• Whether hot exhaust air is being drawn back into the chiller.

For a water-cooled chiller, check:

• Cooling-water temperature.
• Cooling-water flow rate.
• Condenser scaling or blockage.
• Cooling tower operation.

Step 3: Check the Refrigeration System

If the water circuit and heat dissipation system are normal, check the refrigeration system.

Measure and record:

• High-pressure reading
• Low-pressure reading
• Suction temperature
• Discharge temperature
• Compressor operating current
• Evaporator inlet and outlet water temperatures

1. How to Identify the Problem from Pressure Readings

Low Suction Pressure

Possible causes include:

• Insufficient refrigerant
• Refrigerant leakage
• Blocked filter-drier
• Expansion valve malfunction
• Insufficient refrigerant flow

High Discharge Pressure

Possible causes include:

• Dirty condenser
• Poor ventilation
• Excessively high ambient temperature
• Insufficient cooling-water flow
• Cooling fan failure
• Condenser scaling

1. Check Whether the Chiller Capacity Is Sufficient

Sometimes the chiller itself is operating normally, but the cooling load is greater than the chiller’s rated capacity.

For example, if the process generates excessive heat, the chiller may run continuously while the water temperature remains high.

The following should be checked:

• Actual heat load
• Water tank volume
• Water flow rate
• Target water temperature
• Ambient temperature
• Chiller rated cooling capacity
• Operating conditions of the equipment being cooled

1. Practical Example

If the operating conditions are:

Return water temperature: 25°C
Outlet water temperature: 24°C
Compressor: Running continuously
Cooling effect: Very poor

Do not immediately assume that the compressor is defective.

The following items should be checked first:

Refrigerant charge → condenser heat dissipation → evaporator heat exchange → water flow → expansion valve → actual cooling load

A systematic inspection can help locate the fault more quickly and avoid unnecessary replacement of components.

6. Quick Troubleshooting Checklist

Chiller not cooling →

1. Check water level and water flow
2. Check water pump
3. Check water filter and piping
4. Check condenser cleanliness
5. Check cooling fan or cooling-water system
6. Check compressor operation
7. Measure high and low pressure
8. Check refrigerant charge and leakage
9. Check expansion valve
10. Check temperature sensor and controller
11. Check actual cooling load
12. Confirm that the chiller capacity matches the application

Important: Refrigeration-system pressure and refrigerant charging should be checked and serviced by qualified refrigeration technicians using appropriate instruments and procedures.