Common Issues with Refrigeration Equipment: What to Do?

I. What should I do if there is a high-pressure alarm?
Cause analysis:
The flow rate of cooling water (or air) is too small to take away the condensation heat of the compressor.
The temperature of cooling water (or air) is too high, and the heat transfer is not good, so it cannot take away the condensation heat of the compressor.
There is air in the system, which increases the condensation pressure.
Too much refrigerant is charged, and the liquid occupies the effective condensation area, thus increasing the condensation pressure.
The condenser is in disrepair for a long time, and the heat transfer surface is seriously fouled (or there is too much dirt in the air-cooled condenser), which can also lead to an increase in condensation pressure. The presence of scale also has a greater impact on condensation pressure.
Of course, there are many other reasons. It is recommended to consider from three aspects:
There is too much refrigerant in the condenser.
There are other impurities in the refrigeration system, occupying the heat transfer area of the condenser.
The condensation effect of the condenser is not good.
Processing ideas:
Check that the high-pressure pressure control is fine and there is no false alarm.
Touch the condenser of the refrigeration system (air-cooled condenser or water-cooled condenser) by hand. If the condenser is very hot, it means that the heat transfer effect of the condenser is not good. At this time, you can check the problems of cooling water (or condensation fan).
Try releasing a little refrigerant and see!

II. What should I do if there is a low-pressure alarm?
Cause analysis:
There are many reasons for the low evaporation temperature. The mechanism that leads to the low evaporation temperature is that there is little refrigerant in the evaporator or the heat transfer of the evaporator is not good. Listed as follows:
The opening of the expansion valve is small.
The refrigeration system lacks refrigerant.
The capillary tube or expansion valve is blocked.
The filter is blocked.
The air volume of the indoor unit is insufficient.
The evaporator is severely frosted.
Processing ideas:
Check the low-pressure pressure control to confirm that there is no problem with the pressure control and no false alarm.
Check whether there is any dirt in the evaporator blocking the return air of the evaporator (whether scale in the water-cooled evaporator affects heat transfer).
Check the evaporator to see if the evaporator is severely frosted. If the evaporator is severely frosted, check whether there is a problem with the evaporator fan (or chilled water) and eliminate the reason for small air volume (small water volume).
Check whether the expansion valve has faults such as dirt blockage and eliminate the small evaporation pressure caused by the small opening of the expansion valve.

III. What should I do if there is an oil pressure difference alarm?
Cause analysis:
Insufficient refrigeration oil causes insufficient oil level in the compressor crankcase, and the oil pump cannot suck oil.
Dirty oil causes blockage of the oil pump filter.
The oil pressure difference relay malfunctions.
The oil pump fails.
There is a large amount of Freon in the refrigeration oil, resulting in the inability to establish oil pressure.
Liquid return - the harm lies in diluting the lubricating oil.
Processing ideas:
Insufficient refrigeration oil causes insufficient oil level in the compressor crankcase, and the oil pump cannot suck oil.
Dirty oil causes blockage of the oil pump filter.
The oil pressure difference relay malfunctions.
The oil pump fails.
There is a large amount of Freon in the refrigeration oil, resulting in the inability to establish oil pressure.
Liquid return - the harm lies in diluting the lubricating oil.

IV. What should I do if the compressor has thermal protection?
Cause analysis:
Insufficient return gas volume in the system, and the motor is not fully cooled.
Abnormal power supply voltage, phase loss, and motor overload.
Overheating phenomena such as high motor temperature, high exhaust temperature, and scorched lubricating oil caused by problems such as too high condensation pressure.
Processing ideas:
Adjust the intercooler expansion valve to increase the circulation of the system and fully cool the motor. (Check whether the liquid supply pipeline is blocked by the liquid supply stop valve, drying filter, solenoid valve, and filter screen in front of the expansion valve. Check whether the return gas pipeline and the suction filter of the compressor are blocked, and repair if there is a blockage. Check whether there is a lack of refrigerant).
Check whether the three-phase voltage of the power supply is within the standard range and whether the resistance between the phase sequences is balanced.
Insufficient heat dissipation area of the condenser, fouling, insufficient cooling air volume or water volume, and too high temperature of cooling water or air can all lead to too high condensation pressure.
The exhaust temperature is greatly affected by the compression ratio. The larger the compression ratio, the higher the exhaust temperature.

The suction pressure is determined by the evaporation pressure and the resistance of the suction pipeline. Increase the suction pressure and quickly reduce the compression ratio, thereby reducing the exhaust temperature.

V. What should I do if the refrigeration effect is poor and the predetermined temperature cannot be reached?
Cause analysis:
The expansion valve is opened too large or too small. If the expansion valve is opened too large, the compressor itself is severely frosted, and the liquid volume is too large. If the expansion valve is opened too small, the liquid volume is insufficient.
The refrigeration system is blocked and not smooth, such as filter blockage, expansion valve blockage, relevant valves not opened or not fully opened, solenoid valve failure, etc.
Insufficient refrigerant.
The paper gasket on the upper part of the compressor valve plate or the lower part of the cylinder is punctured or broken, or the compressor suction and exhaust valve plates are broken.
Processing ideas:
Adjust the expansion valve to make the compressor reach the best working condition.
Find the blocked part and reason and clean it in time.
Add an appropriate amount of refrigerant according to the actual working conditions of the compressor.
Replace with a new paper gasket or exhaust valve plate.