1. The cooling water inlet temperature is too high:
If the inlet temperature of cooling water is too high, the refrigerant supercooling temperature, condensing temperature and condensing pressure will be too high, the compressor pressure ratio will increase, the shaft power will increase, and the gas transmission coefficient will decrease, thus reducing the refrigeration capacity of the system. Therefore, the overall cooling effect will decrease and the temperature of air-conditioned rooms will rise.

2. Circulating water pump does not turn:
When debugging and running the refrigeration unit, the system circulating water pump should be turned on first. When the circulating water pump does not turn, the outlet temperature of cooling water and the outlet temperature of condenser refrigerant rise most obviously. Due to the sharp decline of condenser cooling effect, the suction temperature and exhaust temperature of compressor also rise rapidly, and the evaporation temperature also rises with the increase of condensation temperature, but the evaporation temperature does not rise as much as the condensation temperature, so the refrigeration efficiency decreases and the temperature of air-conditioned room rises rapidly.

3. The filter is blocked:
Filter blockage means dirty blockage of the system. Under normal circumstances, dirty blockage often occurs at the filter, because the filter screen of the filter separates the channel section and filters out dirt, metal scraps and other sundries, and refrigeration and air conditioning are blocked after a long time.
The result of filter blockage is a decrease in refrigerant circulation, many of which are similar to the over-opening of expansion valve, such as an increase in compressor suction and exhaust temperature, a decrease in compressor suction and exhaust pressure, and a rise in air-conditioned room temperature. The difference is that the filter outlet temperature is getting lower and lower. This is because throttling starts at the filter, which causes the local temperature of the system to decrease. In severe cases, local frost or ice will appear in the system.

4. Overload of air-conditioned room:
Due to the effects of internal disturbance and external disturbance in the room and the influence of various factors, the temperature of the air-conditioned room will rise when the air-conditioned room is overloaded, and finally the temperature index of the normal air-conditioned room cannot be reached. At the same time, the two most affected parameters are compressor suction temperature and exhaust temperature.
Due to the influence of heat capacity of air-conditioned room, it will take a certain time before other parameters are affected obviously.

5. Cooling water flow is too small:
Because of the relationship between cooling water pipe and cooling water valve, the configuration of cooling tower in the system is too small or there is too much scale in the cooling tower, too small cooling water flow and too high cooling water inlet temperature are also common faults.
When the cooling water flow rate is too small, the heat exchange effect of the condenser decreases, so the refrigerant temperature at the outlet of the condenser increases, and the condensing temperature of the refrigerant increases, which reduces the refrigeration coefficient and affects the refrigeration effect.
Under other conditions unchanged, the temperature of air-conditioned room will rise to a certain extent, and the suction temperature of compressor will also rise. But the most obvious change is that the temperature difference at the outlet of cooling water will be larger and larger.