1. Leakage of fluorine refrigerants
[Fault analysis] After the leakage of fluorine refrigerants in the system, the refrigeration capacity is insufficient, the suction and exhaust pressures are low, and the intermittent "squeak" airflow sounds much louder than usual can be heard at the expansion valve. The evaporator is free of frost or a small amount of floating frost. If the expansion valve hole is enlarged, the suction pressure will not change much. After shutdown, the equilibrium pressure in the system is generally lower than the saturation pressure corresponding to the same ambient temperature.
[Exclusion method] After fluorine refrigerants leak, do not rush to fill the system with fluorine refrigerants, but immediately find the leakage point, and then fill it with fluorine refrigerants after repair.
2. Too many fluorine refrigerants are filled after maintenance
[Fault analysis] The number of fluorine refrigerants filled in the refrigeration system after repair exceeds the capacity of the system, and the fluorine refrigerants will occupy a certain volume of the condenser, reduce the heat dissipation area, and reduce the cooling efficiency, and the suction and discharge pressures are common. If the pressure is higher than the normal value, the evaporator will not be frosted, and the temperature in the warehouse will be slowed down.
[Exclusion method] According to the operating procedure, the excess fluorine refrigerants must be released at the high-pressure shut-off valve after a few minutes of the shutdown, and the residual air in the system can also be released at this time.
3. There is air in the refrigeration system
[Fault analysis] Air in the refrigeration system will reduce the refrigeration efficiency. The prominent phenomenon is that the suction and discharge pressure increase (but the discharge pressure has not exceeded the rated value), and the temperature from the compressor outlet to the condenser inlet increases significantly. Due to the presence of air in the system, the exhaust pressure and exhaust temperature both increase.
[Exclusion method] A few minutes after the shutdown, air can be discharged from the high-pressure shut-off valve several times in succession, and some fluorine refrigerants can be filled appropriately according to the actual situation.
4. Low compressor efficiency
[Fault analysis] The low efficiency of the refrigeration compressor refers to the decrease in the actual displacement under the condition that the operating conditions remain unchanged, resulting in a corresponding decrease in the refrigeration capacity. This phenomenon mostly occurs on compressors that have been used for a long time. The wear is large, the matching gap of each part is large, and the sealing performance of the valve is reduced, which causes the actual displacement to decrease.
[Troubleshooting] Check whether the cylinder head paper gasket is broken down and cause leakage; check whether the high and low-pressure exhaust valves are not closed tightly; check the matching clearance between the piston and the cylinder
5. The frost on the surface of the evaporator is too thick
[Fault analysis] The cold storage evaporator used for a long time should be defrosted regularly. If it does not defrost, the frost layer on the evaporator pipeline will become thicker and thicker. When the entire pipeline is wrapped into a transparent ice layer, it will seriously affect the heat transfer. As a result, the temperature in the warehouse does not fall within the required range.
[Exclusion method] Stop defrosting, open the warehouse door to allow air to circulate, or use a fan to accelerate the circulation to reduce the defrosting time.
6. There is refrigerating oil in the evaporator pipeline
[Fault analysis] During the refrigeration cycle, some refrigerating oil remains in the evaporator pipeline. After a long period of use, when there is more residual oil in the evaporator, it will seriously affect the heat transfer effect and cause poor cooling.
[Exclusion method] Remove the refrigerating oil in the evaporator. Remove the evaporator, blow it out, and then dry it. If it is not easy to disassemble, use a compressor to pump air from the entrance of the evaporator, and then use a blowtorch to bake it.
7. The refrigeration system is not unblocked
[Fault analysis] As the refrigeration system is not cleaned, after a certain period of use, dirt gradually accumulates in the filter, and some meshes are blocked, resulting in a decrease in the flow of fluorine refrigerants, which affects the cooling effect. In the system, the expansion valve and the filter at the suction port of the compressor are also slightly blocked.
[Exclusion method] The micro-blocking parts can be removed, cleaned, dried, and then reinstalled.
8. The filter is clogged
[Fault analysis] The desiccant has been used for a long time and becomes a paste to seal the filter, or dirt gradually accumulates in the filter and causes blockage.
[Exclusion method] Remove the filter, clean, dry, replace with a new desiccant, and install it into the system.
9. Leakage of fluorine refrigerants in the temperature sensing package of the expansion valve
[Fault analysis] After the temperature-sensing agent in the expansion valve temperature sensing bag leaks, the two forces below the diaphragm push the diaphragm upwards, the valve hole is closed, and the fluorine refrigerants in the system cannot pass through, resulting in no refrigeration. At this time, the expansion valve does not freeze. Frost, the low pressure presents a vacuum, and no airflow sound can be heard in the evaporator.
[Remedy] Shut down and close the shut-off valve, remove the expansion valve to check whether the filter is blocked, if not, use the mouth to blow the inlet of the expansion valve to see if it is ventilated. It can also be inspected visually or disassembled for inspection, and replaced when damaged.
10. The cold storage cooling effect of the cold air-cooled condenser is poor
① The fan is not turned on.
② The fan motor is damaged.
③ The fan is reversed.
④ The ambient temperature is high (above 40℃).
⑤ The condenser fins are blocked by oil and dust and the air does not circulate.
[Exclusion method] Use a wire brush to remove dust on the surface, or clean it.
11. The cold storage heat dissipation effect of the water-cooled condenser is poor
① The cooling water valve is not opened or opened too small, and the inlet water pressure is too low
② The water control valve is out of order.
③ The scale on the wall of the condenser tube is thick.
[Exclusion method] Check the amount of cooling water. Remove limescale.
12. There is residual air in the system
[Fault analysis] There is air circulation in the system, and the exhaust pressure will be too high, the exhaust temperature will be high, the exhaust pipe will be hot, the cooling effect will be poor, the compressor will run short, and the exhaust pressure will exceed the normal value.
[Remedy] Stop the machine and release air at the exhaust valve hole.
13. Shutdown caused by low suction pressure
[Fault analysis] When the suction pressure in the system is lower than the setting value of the pressure relay, its contact action will cut off the power supply.
[Exclusion method] 1. Leakage of fluorine refrigerants. 2. The system is blocked.
14. The temperature controller is out of control
[Fault analysis] The thermostat is not adjusted properly or the temperature sensor is installed improperly.
[Troubleshooting method] Remove the thermostat to repair its contacts, adjust, and adjust the position of the temperature sensor
15. Sudden downtime caused by other reasons
[Fault analysis] In the process of use and maintenance, it is often necessary to open and close the exhaust, suction, and valve. Sometimes the stop valve is not opened due to negligence, causing the exhaust pressure to rise sharply.
[Remedy] Stop immediately to prevent danger.