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Rotary screw air compressors are very common compressors available on today’s market. They are used for a wide variety of applications across many industries. Like any machine, they are likely to have some troubleshooting issues that will require action.

This article will provide examples of troubleshooting tips for a reciprocating air compressor from a popular manufacturer’s owner’s manual.

Table of Contents

Rotary Screw Air Compressor Troubleshooting Examples

I have picked out this manual for an Eaton rotary screw air compressor which provides tips on how to take action on various troubleshooting issues.

Though these troubleshooting tips are specifically provided by Eaton for one of their models of rotary screw compressors, it is likely that you will be able to transfer this information and apply it to your rotary screw air compressor.

I will recommend reviewing your reciprocating air compressor’s owner’s manual to find the troubleshooting guidance provided by your manufacturer. If you do not have the manual, then search for it online or contact the manufacture directly.

We will take a look at the possible causes, and the correct action to take for the following symptoms:

  • Compressor will not start
  • Compressor shuts down under compression
  • Air pressure is too low
  • Line pressure exceeds upper preset safety limit
  • Air exhaust temperature lower than normal
  • Excessive air exhaust temperature causing compressor to shutdown
  • Excessive oil consumption
  • Pressure relief valve opens repeatedly
  • Water in air sytem
  • Excessive noise level
  • Excessive vibration
  • Black residue on belt guards
  • Shaft seal leak
  • Low air pressure in storage tank while compressor maintains programmed air pressure

Rotary Screw Compressor Will Not Start

Possible CausesCorrect Actions
Electrical power supply problemCheck complete circuit for proper voltage, ensure all electrical connections are secure; once electrical power is restored, press Enter button on the controls.
Blown circuit fuse and/or internal fuseReplace fuses as required.
Poor contact on start push buttonHave an electrician or manufacture of the compressor inspect and replace the push button.
Failed electric motorHave an electrician or manufacturer of the compressor dealer inspect and replace the push button.
Failed compressor pumpAttempt to move by hand to check for free movement of pump. If not possible, contact the manufacturer’s customer service.
Rotary Screw Compressor Will Not Start Possible Causes and Correct Actions Table

Rotary Screw Compressor Shuts Down Under Compression

Possible CausesCorrect Actions
Loss of control voltageReset-Press Enter button on controls. If trouble persists, check line pressure does not exceed the maximum operating pressure of the compressor (specified on the nameplate).
Low incoming voltageWire size for power supply too small.
Contact local power company.
Rotary Screw Compressor Shuts Down Under Compression Possible Causes and Correct Actions Table

Rotary Screw Compressor Air Pressure is Too Low

Possible CausesCorrect Actions
Air demand too highDecrease the air consumption or increase
the number of compressors in the system.
Blocked air filterClean or replace the air filter.
Inlet valve not opening properly which reduces incoming airflowDisassemble and clean the inlet valve.
Apply lubricating oil to the valve.
Improperly adjust pressure regulatorAdjust pressure regulator to proper
settings.
Load solenoid not operating properlyDisassemble and clean solenoid valve.
Replace if needed. Check for proper
voltage – 220V required.
Low oil levelTop up the oil to the correct level.
V-belts slippingAdjust belt tension
Air leakCheck compressor & complete air
system for air leaks.
Compressor running in unload modeCheck pressure switch settings; make
sure unload pressure is set properly.
Rotary Screw Compressor Air Pressure is Too Low Possible Causes and Correct Actions Table

Rotary Screw Compressor Line Pressure Exceeds Upper Preset Safety Limit

Possible CausesCorrect Actions
Control system leak causing
pressure signals to be lost
Check pressure switch for leaks and/or
air restriction. Repair as needed.
Defective pressure switch/sensorCheck for damage to diaphragm and
contacts. Replace if necessary.
Defective solenoid valveReplace valve.
Defective blow-down valveCheck that sump pressure is exhausted
in the atmosphere when the machine is
unloaded. Repair or replace if necessary.
The high-pressure shut-down preset is incorrectly programmedReset to the proper setting.
Additional compressor piped into the system causing preset to be exceededReset additional compressor pressure settings to 145 psi or lower
Rotary Screw Compressor Line Pressure Exceeds Upper Preset Safety Limit Possible Causes and Correct Actions Table

Rotary Screw Compressor Air Exhaust Temperature Lower Than Normal

Possible CausesCorrect Actions
Compressor running under no-load excessivelyReset motor shut-down time
Temperature sensor malfunction Replace temperature sensor
Rotary Screw Compressor Air Exhaust Temperature Lower Than Normal Possible Causes and Correct Actions Table

Rotary Screw Compressor Excessive Air Exhaust Temperature Causing Compressor to Shutdown

Possible CausesCorrect Actions
Low oil levelAdd oil to a sufficient level
Incorrect oil usedDrain all oil and replace it with oil recommended by the manufacturer
Blocked oil filterReplace oil filter
Surrounding temperature too highCheck for air exhaust blockage. Increase air ventilation
Blocked coolerClean cooler
Temperature sensor malfunctionReplace temperature sensor
Cooling fan failureReplace cooling fan
Rotary Screw Compressor Excessive Air Exhaust Temperature Causing Compressor to Shutdown Possible Causes and Correct Actions Table

Rotary Screw Compressor Excessive Oil Consumption

Possible CausesCorrect Actions
Clogged return/scavenge line or orificeClear blockage
Damaged or improperly functioning air/oil separator filterChange air/oil filter
Excessive foamingDrain and change the oil
Oil level too highDrain oil then check at sight glass for proper level
Lubrication system leakCheck all pipes, connections, and components. Repair if necessary
The low minimum pressure in the separator tankMinimum pressure should be around 65 psi depending on make and model
Rotary Screw Compressor Excessive Oil Consumption Possible Causes and Correct Actions Table

Rotary Screw Compressor Pressure Relief Valve Opens Repeatedly

Possible CausesCorrect Actions
Defective pressure reliefReplace valve
Clogged air/oil separatorReplace filter
Rotary Screw Compressor Pressure Relief Valve Opens Repeatedly Possible Causes and Correct Actions Table

Rotary Screw Compressor Water in Air System

Possible CausesCorrect Actions
Defective moisture separator/Drain trapInspect & clean if required; Replace separator if necessary
Trap drain or drain piping blockedInspect & clean
Aftercooler core dirtyInspect & clean
No aftercooler on unitInstall aftercooler
Drain line/drip leg incorrectly installedSlope drain line away from the trap; Install drip leg
No refrigerated or desiccant air dryer in the air systemContact manufacturer
Rotary Screw Compressor Water in Air System Possible Causes and Correct Actions Table

Rotary Screw Compressor Excessive Noise Level

Possible CausesCorrect Actions
V-belts slippingAdjust belt tension or replace belts
Compressor defectiveReplace bearing; contact manufacturer
Enclosure panels not in placeInstall enclosure panels
Loose component mountingInspect & tighten
Shipping brackets in placeRemove shipping brackets
Rotary Screw Compressor Excessive Noise Level Possible Causes and Correct Actions Table

Rotary Screw Compressor Excessive Vibration

Possible CausesCorrect Actions
Loose component mountingInspect & tighten
Motor or compressor bearing failureReplace bearing; contact manufacturer
External sourcesCheck for other sources of vibration, other than the compressor
V-belts slippingAdjust belt tension or replace belts
Shipping brackets in placeRemove shipping brackets
Rotary Screw Compressor Excessive Vibration Possible Causes and Correct Actions Table

Rotary Screw Compressor Black Residue on Belt Guards

Possible CausesCorrect Actions
V-belts looseAdjusted belt tension
Sheave misalignedAlign sheaves
Excessive belt wearReplace belts
Using non-OEM beltUse only OEM parts
Rotary Screw Compressor Black Residue on Belt Guards Possible Causes and Correct Actions Table

Rotary Screw Compressor Shaft Seal Leak

Possible CausesCorrect Actions
Defective shaft sealReplace or contact the manufacturer
Rotary Screw Compressor Shaft Seal Leak Possible Causes and Correct Actions Table

Rotary Screw Compressor Low Air Pressure in Storage Tank While Compressor Maintains Programmed Air Pressure

Possible CausesCorrect Actions
Check valve installed between compressor & storage tankRemove check valve
Air dryer frozen-up restricting airflowBypass dryer
Inline filter between compressor & storage tank is cloggedReplace filter
Rotary Screw Compressor Low Air Pressure in Storage Tank While Compressor Maintains Programmed Air Pressure Possible Causes and Correct Actions Table

FAQs (Frequently Asked Questions)

How do I troubleshoot my air compressor?

To troubleshoot your air compressor, you are best following the guidance in your compressor’s user manual provided by the manufacturer. This will contain all the possible issues you may encounter, why they have been encountered, and steps to take to fix them. If you cannot locate your compressor’s user manual, you should contact the manufacturer directly.

Do rotary screw compressors run constantly?

If the rotary screw has a 100% duty cycle and is rated for continuous use then yes, the compressor can run constantly. They typically have better cooling systems to allow them to run for extended periods of use.

Additional Troubleshooting Pages

Air Compressor Types Troubleshooting

Air Compressor Part Specific Troubleshooting


If you have any questions regarding rotary screw air compressor troubleshooting, please leave a comment below, with a photo if applicable, so that someone can help you!