The air curtain display cabinet is not only fashionable in appearance design, but also elegant in appearance; Humanized design increases commodity display. At the same time, customers can pick up goods conveniently and quickly when shopping; The design of evaporator is enlarged, and the heat exchange efficiency is improved.
Common faults of air curtain display cabinet
(1), leakage: refers to refrigerant leakage; Leakage caused by electrical (line, machine body) insulation damage, etc.
(2) Blockage: refers to the dirty blockage and ice blockage of the refrigeration system; Air filter is blocked; The air inlet and air outlet are blocked by obstacles; The refrigerant oil of compressor turns black, the upper and lower bearing sleeves fall off or wear, the connecting rod breaks, the friction surfaces of crankshaft and bearing, crankshaft and connecting rod have scratch marks, the motor rotor has wear marks, and the intake and exhaust valves are intact.
(3), disconnection: refers to the disconnection of electrical lines; The fuse is blown; The contact of overload protector is disconnected due to overheating or excessive current; Due to the abnormal pressure in the refrigeration system, the contact of the pressure relay is disconnected.
(4) Burning loss: refers to the burning loss of compressor motor winding, fan motor winding, solenoid valve coil, relay coil and contact.
(5), card: refers to the compressor stuck, the fan stuck, the moving parts bearing stuck, etc.
(6), damage: refers to the compressor valve plate damage, piston sticking, fan blade fracture and parts damage.
We can analyze the common faults of the air curtain display cabinet as follows:
Causes of compressor motor burning:
① The motor temperature rise is too high. Because the motor of the fully enclosed compressor is cooled by return air, the working conditions are even worse when the heat pump is used for mechanical heating in winter, especially when the ambient temperature is very low, the heat exchange is very small, the refrigerant circulation is also small, and the return air pressure is low. In addition, the defrosting on the electronic control is not timely and thorough, which will lead to insufficient cooling of the motor and heating of the coil. This continuous heating will form high temperature, and PTC is insensitive to small current response under low load. Therefore, after the compressor is started several times, when it does not reach a higher temperature, insulation will be damaged due to overheating, and the motor will be short-circuited and burned.
② The interior of the refrigeration system is unclean and contains impurities, which corrodes and wears the motor coil, resulting in short circuit burning.
Causes of compressor jamming: From the anatomical phenomenon of this kind of faulty compressor, there is no shortage of oil inside the compressor, and the shaft locking is caused by instantaneous poor lubrication, and the main reason for poor lubrication is that the oil quality of lubricating oil has changed, and the oil level has been diluted or raised by refrigerant liquid.
In view of the above analysis, we can formulate corresponding improvement measures. The basic methods of judging air curtain display cabinets are: seeing, listening, touching, measuring and analyzing.
1. Look: carefully observe the working conditions of all parts of the air curtain display cabinet, focusing on the refrigeration system, electrical system and air system to determine whether it works normally.
(1) Refrigeration system: Observe whether there are cracks, damages, frosting and dew condensation in each pipeline of the refrigeration system; Whether there is collision or friction between the refrigeration pipeline, the pipeline and the shell, especially whether there is leakage at the welding and joint of the refrigerant pipeline, and whether there is oil pollution (there is a certain amount of refrigeration oil in the refrigeration system), you can also wipe the welding and joint of the pipeline with clean soft cloth and soft paper to observe whether there is oil pollution to judge whether there is leakage.
(2) Electrical system: Observe whether the fuse of the electrical system is blown, whether the insulation of the electrical leads is intact, whether the circuit board is damaged, whether the connectors are loose, etc. In particular, whether the electrical connection is in good contact, the wiring screws and connectors are easy to loosen, leading to poor contact.
(3) Ventilation system: Observe whether there is too much dust on the air filter, heat exchanger coil and fins; Whether the air inlet and air outlet are unblocked; Whether the fan and blades are operating normally; Whether the wind is normal, etc.
2. Listen: Listen carefully to whether the compressor of the air curtain display cabinet is working normally, whether there is abnormal noise, whether the fan is running noisily, whether the noise is too large, etc. In the operation of air curtain display cabinets, generally, the vibration is slight and the noise is small, generally below 50DB. If the vibration and noise are excessive, the possible reasons are:
(1) is improperly installed. The bracket size is inconsistent with the unit, it is not firmly fixed, or there is no damping rubber or foam plastic pad. The vibration and noise of the air curtain display cabinet will increase during operation. Especially at the beginning and stop.
(2) Abnormal vibration of compressor. Poor installation of base, uneven feet, poor installation of shock-proof rubber or spring or poor shock-proof effect, etc. If there is a fault inside the compressor, such as valve plate rupture, liquid hammer, etc. , but also make abnormal sounds.
(3) Fan collision. Improper installation or deformation of fan blades will produce collision sound. The fan may collide with the wall shell and chassis, the axis of the fan will move, and the blades will make a collision sound when they are out of balance; If there is a foreign body in the fan, the blades will also collide with it.
3. Touch: Touch the relevant parts of the air curtain display cabinet by hand to feel its cold, heat and vibration, which is helpful to judge the nature and location of the fault. In general, the temperature of the condenser gradually decreases from top to bottom, and the temperature in the lower part is slightly higher than the ambient temperature. If the whole condenser is not hot or the upper part is slightly warm, or although it is hot, the temperatures of two adjacent tubes are obviously different, it is abnormal. Evaporator Under normal circumstances, if you immerse your fingers in the water on the surface of the evaporator, you will feel cold and sticky. In general, the capillary at the dryer and outlet should feel warm (slightly higher than the ambient temperature, and basically the same as the pipeline temperature at the end of the condenser). If the temperature is lower than the ambient temperature, the temperature difference between the condensation on the surface and the capillary section is abnormal. Under normal circumstances, the temperature of the suction pipe 200MM away from the compressor should be close to the ambient temperature.
4. Measurement: In order to accurately judge the nature and location of the fault, it is often necessary to check and measure the performance parameters and status of the air curtain display cabinet with instruments and meters. If a leak detector is used to check whether there is refrigerant leakage; Use a multimeter to measure whether the power supply voltage, grounding current of each terminal and working current meet the requirements, and the computer-controlled air conditioner should also measure whether the potential of each control point is normal.
5. Analysis: Most of the results obtained by the above inspection methods can only reflect a certain local state. The parts of the air curtain display cabinet are interrelated and influence each other. A fault phenomenon may have many reasons, and a reason may also produce many faults. Therefore, the local factors should be comprehensively compared and analyzed, so as to comprehensively and accurately determine the nature and location of the fault.