There are five kinds of substances in the circulation of refrigeration system, such as refrigerant, oil, water, air and other impurities. The former two substances are necessary to ensure the normal operation of the system, while the latter three substances are harmful to the system, but they cannot be absolutely eliminated. At the same time, the refrigerant itself has three states: vapor phase, liquid phase and vapor-liquid mixed phase. Therefore, once the air-conditioning refrigeration system fails, its symptoms and causes are complicated. Below, list common faults of air conditioning and refrigeration system:
1, The fan does not turn:
There are two reasons why the fan does not turn: first, the electrical fault, the control circuit is not connected; Second, mechanical failure of fan shaft.
When the room air conditioner fan does not turn, the temperature of the air-conditioned room will rise, and the suction pressure and discharge pressure of the compressor will drop to a certain extent. After the air-conditioning fan does not turn, the heat exchange efficiency of the heat exchange coil in the air-conditioned room decreases, and when the heat load of the air-conditioned room is constant, the temperature of the air-conditioned room will rise.
Due to insufficient heat exchange, the temperature of the refrigerant in the heat exchange coil will decrease compared with the original temperature, that is, the evaporation temperature will decrease and the refrigeration coefficient of the system will decrease. The outlet temperature of the evaporator felt by the thermal expansion valve also decreases, resulting in a smaller opening of the thermal expansion valve and a corresponding decrease in refrigerant, so the suction and exhaust pressures all decrease. The overall effect of the decrease of refrigerant flow and refrigeration coefficient makes the cooling capacity of the system decrease.
2, Cooling water inlet temperature is too low:
With the decrease of cooling water temperature, the compressor discharge pressure, discharge temperature and filter outlet temperature all decrease. However, the temperature of the air-conditioned room remains unchanged, because the cooling water temperature has not dropped to the extent that it will affect the cooling effect. If the cooling water temperature drops to a certain degree, the condensing pressure will also decrease, which will reduce the pressure difference on both sides of the thermal expansion valve, the circulation capacity of the thermal expansion valve will also decrease, and the refrigerant will also decrease, so the refrigeration effect will decrease.
