What are the common faults in engine cooling systems?

[AbelMarie]

Common faults in engine cooling systems are as follows: Low exhaust temperature in the refrigeration system: Low exhaust pressure, although the phenomenon appears on the high-pressure side, the cause mostly originates from the low-pressure side. Refrigeration system experiencing liquid return: For small refrigeration systems using capillary tubes, excessive refrigerant charging can cause liquid return. High suction temperature in the refrigeration system: Insufficient refrigerant charge in the system or too small an expansion valve opening can lead to inadequate refrigerant circulation, resulting in less refrigerant entering the evaporator, high superheat, and consequently high suction temperature. Refrigeration system with liquid start-up: The phenomenon of violent foaming of lubricating oil in the compressor is called liquid start-up. Refrigeration system experiencing oil return: Oil shortage can cause severe lubrication deficiency. The root cause of oil shortage is not the amount or speed of oil running in the compressor, but poor oil return in the system. Evaporation temperature in the refrigeration system: Temperature greatly affects refrigeration efficiency. For every 1-degree decrease, 4% more power is required to produce the same cooling capacity. Therefore, appropriately increasing the evaporation temperature, when conditions permit, is beneficial for improving the efficiency of air conditioner refrigeration. Excessive exhaust temperature in the refrigeration system: The main reasons for excessively high exhaust temperature include high return gas temperature, large motor heating, high compression ratio, high condensing pressure, adiabatic index of the refrigerant, and improper refrigerant selection. Adding fluorine to the refrigeration system: When the amount of fluorine is small or its regulating pressure is low (or partially blocked), the valve cover (bellows) of the expansion valve, and even the liquid inlet, may frost; when the amount of fluorine is very small or almost none, there is no visible reaction on the expansion valve, only a slight hissing sound of airflow can be heard. Low suction temperature in the refrigeration system: The expansion valve opening is too large.