Refrigeration Systems: Common Issues and Solutions

Refrigeration Systems_ Common Issues and SolutionsYour refrigeration system must work well. Failure in the system could spell doom to your business.  System breakdowns can often be avoided with regular maintenance.

When equipment failures are unavoidable, and we have to adjust accordingly. It is essential to know what to do when the worst happens. Here are some common issues that may arise among commercial refrigeration units.

1. Undercharging Refrigeration System


You can tell an undercharging refrigeration system when:

  • The compressor is running hot and the performance drops.
  • There is also a drop in suction and discharge pressures.
  • You may also notice vapor bubbles in the liquid sight glass.
  • The condenser has suspiciously low readings.
  • The compressor tests low ammeter readings.
  • The cold rooms are warmer than usual.
  • The compressor runs for longer than usual.


Refrigerant leakage can cause undercharging. Refrigerant leakage can occur at the shaft seal, flange couplings, and valve gaskets. Undercharging may also arise from blockages at the expansion valve or evaporator.


Check for refrigerant leakages at the shaft seal, flange couplings, and valve gaskets. Clean the filters and driers. Replace the lost refrigerant with fresh alternatives. Follow and abide by the manufacturer’s instructions.

2. Overcharge of the Refrigeration System

An overcharged refrigeration system is one running on more refrigerant that it can handle.

Here are the indicators of an overcharged system:

  • High condenser gauge readings.
  • Abnormal start and stop sequences of the compressor.
  • High suction and discharge pressures.


Overcharge of refrigeration systems may arise from excessive refrigerant levels. The inclusion of air in the system may also lead to an overcharge.


Drain the excessive refrigerant from the system. You can accomplish this by connecting a cylinder to the charging valve (liquid line). Start the compressor and operate the charging valve.

If air is the cause for the overcharge, correct it by purging the air.

3. Moisture Within the System

This problem comes with the ingress of air in the system. The humidity in the air may cause the expansion valve to freeze. As a result, the refrigeration system may indicate signs of undercharging. Moisture may also cause corrosion within the system.


In case of minor moisture within the system, renew the silica gel. You can also drain the refrigerant and pump-out all the air in the system.

4. Air in the System


  • Overheating compressor with high discharge pressures.
  • Presence of air bubbles in the liquid sight glass in the condenser.
  • The compressor runs for extended periods.
  • Air may cause the gauge pointer to jump.


Air may enter the system during charging. freon-12 requires low working pressure. Sometimes when you use freon-12 air leaks may occur at the suction lines.


You can remove air from the system via the condenser. Leave the condenser cooling water on. Vent out the air from the top of the condenser. Connect a collecting cylinder to the purging line. Open the line to drain out the air.

After purging the air, do not forget to seal the purge valve tightly. Check the refrigerant levels. Charge the refrigeration system appropriately with fresh refrigerant. Take all safety precautions into account as you restart the compressor.

5. Oil in the Refrigeration System


  • You may notice that the temperature is not dropping in the cold room as usual.
  • Excessive frost on the suction line
  • The compressor runs for extended periods
  • A drop in lubrication levels
  • A drop in refrigerant levels


  • A malfunctioning oil separator could cause a leak of oil in the system. 
  • Worn-out compressor linings and defective pistons.
  • High capacity current at the start of the refrigeration cycle.


  • Check and replace the oil separator if defective.
  • Clean the drier if necessary
  • Drain the evaporator coil to remove traces of oil
  • Increase the evaporator and condenser temperature differentials to defrost the suction pipe.
  • Warm the pipes with a blow torch.

6. Refrigerant Flooding

Flooding is when liquid seeps back to the suction of the refrigerant compressor. This problem may arise from incorrectly adjusted or faulty expansion valves. It may also occur from leakage at the solenoid valve. Overcharging the refrigerant system may also cause refrigerant flooding.

If not corrected, flooding may ice the evaporator or damage the compressor. 


Drain the excessive refrigerant from the system. You can accomplish this by connecting a cylinder to the charging valve (liquid line). Start the compressor and operate the charging valve.



The health of your refrigeration system could affect your business’ bottom-line. Regular maintenance and checks can prolong the life of your refrigeration system, but some mechanical issues may occur regardless. If you find that you need a replacement compressor, consult a trusted compressor remanufacturer. And remember: Always adhere to the manufacturer’s instructions and specifications.


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