Cause analysis of compressor high pressure alarm and low pressure alarm in refrigeration system

The refrigeration system is usually equipped with high and low pressure switch, which is used to control the suction end and exhaust end of the refrigeration compressor, so as to prevent damage to the compressor due to the low suction pressure and high exhaust pressure of the system.To summarize, the causes of compressor exhaust high pressure alarm and return air low pressure alarm are:

Causes of compressor exhaust high pressure alarm:

① false alarm caused by high voltage switch fault or controller interference;

② there are many dust or foreign objects in the air-cooled condenser, which leads to the decrease of cooling and condensing capacity;

③ power failure or failure of fan of air-cooled condenser;

④ the temperature switch of air-cooled condenser is abnormal;

⑤ water flow loss or abnormal cooling water temperature of water-cooled condenser;

⑥ the exhaust pipeline of the compressor is abnormal, and the oil or foreign matter is blocked;

⑦ too much refrigerant injection.

Causes of low pressure alarm of compressor return gas:

① false alarm caused by low voltage switch fault or controller interference;

② the filter screen of indoor unit is dirty and blocked, resulting in insufficient evaporation air volume;

③ failure of indoor fan, shutdown or speed drop;

④ the temperature set point is wrong and the return air temperature is too low;

⑤ the copper pipe of refrigeration system is too long;

⑥ the area of air inlet or outlet duct becomes smaller (with air duct unit);

⑦ the drying filter is dirty or the copper pipe is blocked by oil;

⑧ the solenoid valve cannot be opened, and the expansion valve fails;

⑨ the delay setting of cold start is not enough, so it is difficult to start in winter;

⑩ the cooling effect of condenser is too good;

⑪ insufficient injection of condenser or refrigerant leakage;

⑫ the liquid return pipe is flattened, resulting in the liquid return not smooth.