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Scroll air compressors are positive-displacement type compressors that are commonly used in various applications. Of course, from time to time, something is going to hinder the scroll compressor’s performance. Therefore, it is important to understand the troubleshooting steps you can take when you encounter such issues so that you can find a solution to your problem.

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

Table of Contents

Scroll Air Compressor Troubleshooting Examples

I have picked out this manual for a Quincy scroll air compressor which provides tips on how to take action on various troubleshooting issues.

Though these troubleshooting tips are specifically provided by Quincy 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 scroll 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 manufacturer directly to obtain it.

It’s very common for scroll compressors to have built-in refrigerated dryers, and so, these troubleshooting tips also include ones for built-in refrigerated dryers. To learn more about them, visit our Refrigerated Air Dryer Guide – Best Refrigerated Air Dryers!

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

  • The compressor does not start
  • The compressor does not stop and/or the safety valve blows
  • The pressure difference between stopping and starting cannot be adjusted
  • Compressor capacity or pressure below normal
  • Compressor overheating and/or shut down by an air temperature switch
  • The Dew point is too high
  • Condenser pressure too high or too low
  • Motor refrigerant compressor stops or does not start
  • Evaporator pressure is too high or too low
  • Condensate trap continuously discharging air and water
  • Electronic condensate drain inoperative

Scroll Compressor Does Not Start

Possible CausesCorrect Actions
Pressure too highThe compressor will start again when the pressure drops to starting pressure.
On/off switch malfunctioning or loose connectionHave electrical connections checked? Test switch and replace if necessary.
Thermal overload switchRestart after cooling down.
Switch open or motor protection relay trippedWait for the switch to cool down. Reset the overload relay and replace the switch if necessary.
Air pressure switch out of orderHas the valve been replaced?
Scroll Compressor Does Not Start Possible Causes and Correct Actions Table

Scroll Compressor Does Not Stop and/or Safety Valve Blows

Possible CausesCorrect Actions
The Air pressure switch opens too late or not at allReadjust switch and replace if necessary.
The safety valve opens too soonHas the valve been replaced?
Scroll Compressor Does Not Stop and/or Safety Valve Blows Possible Causes and Correct Actions Table

Scroll Compressor Pressure Difference Between Stopping and Starting Cannot Be Adjusted

Possible CausesCorrect Actions
Air pressure switch out of orderReplace if necessary
Scroll Compressor Pressure Difference Between Stopping and Starting Cannot Be Adjusted Possible Causes and Correct Actions Table

Scroll Compressor Capacity or Pressure Below Normal

Possible CausesCorrect Actions
Air consumption exceeds the capacity of the compressorCheck equipment connected.
Choked air filterRemove and check the filter. Replace if necessary.
Safety valve leakingReplace valve.
Drive belts slippingCheck the condition of belts and belt tension. correct or replace as required.
Compressor element out of orderConsult the manufacturer.
Scroll Compressor Capacity or Pressure Below Normal Possible Causes and Correct Actions Table

Scroll Compressor Overheating and/or Shut-down by Air Temperature Switch

Possible CausesCorrect Actions
Insufficient compressor coolingClean compressor element fins and fan. Improve ventilation of compressor room. Reset overload relay if necessary.
Cooling fans out of orderCheck and correct, and reset the overload relay if necessary.
Temperature shutdown switch out of orderReplace switch.
Scroll Compressor Overheating and/or Shut-down by Air Temperature Switch Possible Causes and Correct Actions Table

Scroll Compressor Refrigerated Dryer Dew Point Too High

Possible CausesCorrect Actions
Air inlet temperature too highCheck and correct.
Fuses blownCheck fuses and remedy the cause.
Shortage of refrigerantHas the circuit been repaired or recharged?
The refrigerant compressor does not runSee table below.
Evaporator pressure is too highSee table below.
Condenser pressure is too highSee table below.
Scroll Compressor Refrigerated Dryer Dew Point Too High Possible Causes and Correct Actions Table

Scroll Compressor Refrigerated Dryer Condenser Pressure Too High or Too Low

Possible CausesCorrect Actions
Fan control switch out of orderReplace the switch.
Condenser fan motor out of orderHave the fan motor inspected.
Ambient temperature too highImprove ventilation of compressor room.
Condenser externally cloggedClean condenser.
Scroll Compressor Refrigerated Dryer Condenser Pressure Too High or Too Low Possible Causes and Correct Actions Table

Scroll Compressor Refrigerated Dryer Motor Refrigerant Compressor Stops or Does Not Start

Possible CausesCorrect Actions
The internal thermal protection of the motor has trippedThe compressor will restart when the motor windings have cooled down.
Electric power supply to refrigerant compressor interruptedCheck and correct as necessary.
Scroll Compressor Refrigerated Dryer Motor Refrigerant Compressor Stops or Does Not Start Possible Causes and Correct Actions Table

Scroll Compressor Refrigerated Dryer Evaporator Pressure Is Too High or Too Low

Possible CausesCorrect Actions
Condenser pressure too high or too lowSee table below.
Shortage of refrigerant Have the circuit repaired or recharged.
Hot gas bypass valve incorrectly set or out of orderHave the valve adjusted or replaced.
Scroll Compressor Refrigerated Dryer Evaporator Pressure Is Too High or Too Low Possible Causes and Correct Actions Table

Scroll Compressor Refrigerated Dryer Condensate Trap Continuously Discharging Air and Water

Possible CausesCorrect Actions
Automatic drain out of orderHave the drain checked and replaced as necessary.
Scroll Compressor Refrigerated Dryer Condensate Trap Continuously Discharging Air and Water Possible Causes and Correct Actions Table

Scroll Compressor Refrigerated Dryer Electronic Condensate Drain Inoperative

Possible CausesCorrect Actions
Drain system cloggedClean the filter of the automatic drain by opening the manual drain valve. Check the functioning of the drain by pushing the test button.
Scroll Compressor Refrigerated Dryer Electronic Condensate Drain Inoperative Possible Causes and Correct Actions Table

FAQs (Frequently Asked Questions)

How do I know if my scroll compressor is bad?

You will know if your scroll air compressor is bad if it is not working as efficiently as it should. It may be that the scroll compressor does not start, does not stop, and/or the safety valve blows, the pressure difference between stopping and starting cannot be adjusted, the capacity or pressure is below its normal level, or the scroll compressor is overheating and/or shut-down by an air temperature switch.

What causes scroll compressor failure?

Some of the most common causes of scroll compressor failure include system leaks, dirty/clogged filters, dirty condensers, rapid loading/unloading, misadjusted controls, and wrong oil for the system’s refrigerant.

Additional Troubleshooting Pages

Air Compressor Types Troubleshooting

Air Compressor Brand Specific Troubleshooting

Air Compressor Brand/Problem Specific Troubleshooting

Air Compressor Part Specific Troubleshooting


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