【Essential for Equipment Maintenance】Self-Diagnosis and Troubleshooting Guide for Refrigeration Scroll Compressors

Self-Diagnosis Guide for Scroll Compres Cooling Failure

Introduction

When your air conditioning or refrigeration system fails to cool, the compressor is often the primary suspect. This guide provides a step-by-step self-diagnosis procedure based on the standard troubleshooting process for scroll compressors. Please follow these steps carefully to identify the root cause.

Step 1: Check Suction and Discharge Pressure

•  Action: Use a pressure gauge to measure the suction pressure (inlet) and discharge pressure (outlet) of the compressor.

•  Analysis:

•    If pressure is normal: Proceed to check the evaporator (evaporator coil) for issues like frost buildup or blockage.

•    If suction pressure is low: This indicates a refrigerant shortage or a problem with the expansion valve.

       Solution: Recharge the refrigerant or adjust the expansion valve to bring the suction pressure back to the normal operating range.

Step 2: Check for Suction and Discharge Gas

•  Action: Observe if the compressor is sucking in and discharging gas.

• Analysis:

•    If there is suction and discharge: Check the compressor's noise level.

•    If there is no suction or discharge: Check if the compressor is running idle (spinning without compressing).

Step 3: Check for Abnormal Noise

•  Action: Listen carefully to the compressor while it is running.

• Analysis:

•  If there is a metallic impact sound or other abnormal noise:

           Cause: This usually indicates a broken crosshead (crosshead fracture) or issues with the lubricating oil (carbonization or lack of oil).

           Solution: Immediate shutdown and professional repair are required.

• If there is no abnormal noise but the compressor is running idle:

     Action: Check the power supply phase sequence.

     Solution: If the phase sequence is reversed, adjust the power supply wiring to correct the rotation direction.

Step 4: Check Operating Current

•  Action: Measure the operating current of the compressor.

•  Analysis:

•     If there is current but the compressor is not running:

• Action: Turn off the power for 4 hours, then restart.

• Analysis:

•   If it recovers: The issue was likely insufficient return gas, leading to inadequate cooling and triggering the discharge temperature overheat protection.

•      Solution: Recharge refrigerant or adjust the expansion valve.

•   If it does not recover: Check for a detached scroll disc and rotor.

•  Action: Gently tap the top of the compressor with a rubber hammer.

•  Analysis:

• If it recovers: The compressor can be used normally.

• If it does not recover: The compressor is damaged and needs replacement.

• If there is no current:

• Action: Check the compressor motor winding.

• Analysis:

If the winding is open circuit: Turn off the power.

• Action: Wait for 4-12 hours for the internal thermal protector to reset.

• Analysis:

• If it recovers after 2 hours: The issue was insufficient return gas, inadequate cooling, and overheating.

Solution: Recharge refrigerant or adjust the expansion valve.

• If it does not recover: The compressor winding is burnt out and needs replacement.

Conclusion

By following this flowchart, you can systematically narrow down the cause of the cooling failure.

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