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Rotary screw compressors are widely used in various industries due to their efficiency, reliability, and ability to provide a continuous supply of compressed air. However, like any mechanical equipment, they can encounter issues that affect their performance. Effective troubleshooting involves identifying the symptoms, understanding the potential causes, and applying the appropriate corrective actions. This essay explores common problems with rotary screw compressors and offers detailed troubleshooting guidance for each issue.

Common Issues and Troubleshooting Steps

1. Compressor Not Starting

Symptoms: The compressor fails to start or has difficulty starting.

Possible Causes:

  • Electrical issues (blown fuses, tripped breakers, faulty wiring)

  • Low oil levels or wrong oil type

  • Faulty starter or contactor

  • Overload protection activated

  • Faulty pressure switch

Troubleshooting Steps:

  1. Check Electrical Supply: Ensure that the compressor is connected to a reliable power source. Inspect for blown fuses, tripped circuit breakers, and damaged wiring. Reset the breakers if necessary.

  2. Inspect Oil Levels: Verify that the oil level is within the recommended range and that the correct type of oil is being used.

  3. Examine Starter and Contactor: Test the starter and contactor for faults. Replace them if necessary.

  4. Overload Protection: Reset the overload protection switch and ensure that the compressor is not overloaded.

  5. Pressure Switch: Check the pressure switch for proper operation. Replace it if it’s faulty.

2. Compressor Overheating

Symptoms: The compressor shuts down due to high temperature, or you observe unusually high operating temperatures.

Possible Causes:

  • Insufficient ventilation

  • Dirty or clogged oil cooler

  • Low oil levels or incorrect oil

  • Malfunctioning thermostatic valve

  • Faulty temperature sensor

Troubleshooting Steps:

  1. Ensure Proper Ventilation: Verify that the compressor is installed in a well-ventilated area and that the cooling fans are operating correctly.

  2. Clean the Oil Cooler: Inspect and clean the oil cooler to ensure it is free from dust, dirt, and debris.

  3. Check Oil Levels: Confirm that the oil level is adequate and that the correct type of oil is being used. Top up or change the oil if necessary.

  4. Thermostatic Valve: Test the thermostatic valve to ensure it is functioning properly and regulating the oil flow. Replace it if defective.

  5. Temperature Sensor: Check the temperature sensor for faults and replace it if necessary.

3. Excessive Noise

Symptoms: The compressor produces unusual or excessive noise during operation.

Possible Causes:

  • Loose or damaged components

  • Worn bearings

  • Misalignment of drive components

  • Vibration issues

  • Air intake filter clogged

Troubleshooting Steps:

  1. Inspect Components: Examine the compressor for loose or damaged parts. Tighten or replace components as needed.

  2. Check Bearings: Inspect the bearings for wear and replace them if necessary.

  3. Align Drive Components: Ensure that the motor and compressor shafts are properly aligned.

  4. Address Vibration: Check for sources of vibration and secure the compressor to reduce movement.

  5. Clean Air Intake Filter: Clean or replace the air intake filter to ensure unobstructed airflow.

4. Air Leaks

Symptoms: Decreased air pressure or the compressor running continuously.

Possible Causes:

  • Leaking hoses or fittings

  • Faulty pressure relief valve

  • Leaking seals or gaskets

Troubleshooting Steps:

  1. Inspect Hoses and Fittings: Check all hoses and fittings for leaks. Tighten connections or replace damaged hoses.

  2. Pressure Relief Valve: Test the pressure relief valve for proper operation. Replace it if it is leaking.

  3. Check Seals and Gaskets: Inspect seals and gaskets for signs of wear or damage. Replace them if necessary.

5. Oil Carryover

Symptoms: Excessive oil in the compressed air, resulting in oil contamination in tools and equipment.

Possible Causes:

  • Overfilled oil reservoir

  • Worn or faulty separator element

  • Incorrect oil type

  • Malfunctioning oil return system

Troubleshooting Steps:

  1. Check Oil Level: Ensure that the oil level is not overfilled. Drain excess oil if necessary.

  2. Separator Element: Inspect the separator element for wear or damage. Replace it if necessary.

  3. Correct Oil Type: Verify that the correct type of oil is being used as specified by the manufacturer.

  4. Oil Return System: Test the oil return system to ensure it is functioning properly and returning oil to the sump.

6. Pressure Drops

Symptoms: Inadequate air pressure at the point of use or fluctuating pressure levels.

Possible Causes:

  • Undersized piping or air lines

  • Air leaks in the system

  • Clogged filters

  • Inadequate compressor capacity

Troubleshooting Steps:

  1. Check Piping Size: Ensure that the piping and air lines are appropriately sized for the air demand.

  2. Inspect for Leaks: Identify and repair any air leaks in the system.

  3. Clean or Replace Filters: Inspect and clean or replace the air filters to ensure proper airflow.

  4. Evaluate Compressor Capacity: Assess whether the compressor capacity meets the air demand. Upgrade the compressor if necessary.

Preventive Maintenance

Preventive maintenance is essential for minimizing downtime and extending the life of a rotary screw compressor. Key maintenance practices include:

  1. Regular Inspections: Conduct routine inspections to identify and address potential issues before they become significant problems.

  2. Oil and Filter Changes: Regularly change the oil and replace filters according to the manufacturer’s recommendations.

  3. Monitor Operating Parameters: Continuously monitor temperature, pressure, and other operating parameters to detect anomalies early.

  4. Clean Components: Keep the compressor and its components clean to prevent dirt and debris buildup.

  5. Service Records: Maintain detailed service records to track maintenance activities and identify recurring issues.


Troubleshooting rotary screw compressor issues requires a systematic approach to identify symptoms, determine causes, and implement solutions. By addressing problems promptly and maintaining a regular preventive maintenance schedule, operators can ensure that their compressors operate efficiently, safely, and reliably. Proper care and timely intervention not only minimize downtime and repair costs but also extend the lifespan of the equipment, ensuring a consistent supply of compressed air for various industrial applications.

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