Article source: Beijing Ronshen Refrigerator After-sales Service Phone Number http://blog.tianya.cn/blogger/blog_main.asp?BlogID=3465372.
Analysis and Maintenance: In response to the aforementioned phenomenon, first check whether the drip tray has water when the refrigerator can cool. The absence of water is generally caused by an electrical circuit fault rather than a refrigeration system fault. If it's an electrical circuit fault, before checking the circuit, one should have a basic understanding of the general working principle of the defrosting circuit. This will greatly help in quickly determining the fault point. When the moving contact point of the defrost timer exactly connects with the static contact point, the compressor circuit is connected, starting the next cooling cycle operation, and the defrost timer clock motor also operates simultaneously. The defrost timer clock motor and the defrost heating element are connected in series in the same circuit. Since the DC resistance of the defrost timer clock motor (measured around 8kΩ) is 25 times greater than that of the defrost heating element (measured at 320Ω), the voltage on the defrost heating element is only 1/25th of the input voltage. When the input voltage is 220V, the voltage on the defrost heating element is only 9V. In other words, all the voltage is applied to the defrost timer clock motor. When the cumulative operating time of the defrost timer reaches 8 hours, its moving contact point connects with the static contact point, at which time the circuit is in the defrost state. Because the internal resistance of the defrost thermostat is very small, it is equivalent to short-circuiting the defrost timer (which has high internal resistance) and putting it into a stop state. The input voltage is entirely applied to the drainage heating element and the defrost heating element, heating the evaporator for defrosting. When the frost layer on the surface of the evaporator is completely melted due to the rise in temperature, the defrost thermostat disconnects at around 13°C, cutting off the circuit to the defrost heater, stopping the heating of the defrost heating element on the evaporator. At the same time, the defrost timer starts operating, connecting the circuit of the compressor (i.e., the moving contact point disconnects from the static contact point and reconnects). After the compressor resumes the next cooling cycle operation, the surface temperature of the evaporator drops quickly. When it drops below 5°C, the defrost thermostat begins to reset, reconnecting the circuit to the defrost heater, waiting for the next cycle of heating defrost.
(1) For frost-free refrigerators, first check if the fan motor is burnt out or jammed. You can also use the R1Ω range of a multimeter to measure whether the DC resistance value of the fan motor is around 300Ω. If the resistance value is too low or open, then the motor is damaged. Most fan motor open circuits are caused by the fuse at one end of the fan motor wire burning out. Replacing the same specification fuse can eliminate the fault. If the fan coil is burnt out, you can rewind it or replace it with a new fan motor. If the fan is jammed, washing it with compressor oil can eliminate the fault.
(2) Use the R1kΩ range of a multimeter to measure the DC resistance value of the defrost timer clock motor, which should be about 8kΩ. If the resistance value is too low, then there is a short circuit in the coil part; if the resistance value is too high, then there is poor contact in the coil, and the defrost timer should be replaced. If the resistance value is normal, under power-on conditions, check if the manual control knob axis of the defrost timer rotates. If it does not rotate, there is a fault in the internal mechanical gears, and it is recommended to replace the defrost timer.
(3) Use the R1Ω range of a multimeter to measure the defrost thermostat, which should be open under normal temperature. Place the defrost thermostat inside the refrigerator freezer compartment, and its resistance should be zero. If measuring it inside the refrigerator freezer compartment shows no conduction or several dozen ohms of resistance, then it is damaged and needs to be replaced.
(4) Use the R1Ω range of a multimeter to measure the defrost heating element and the drainage heating element (the two heating elements are in parallel), and their resistance should be around 320Ω. If the measured resistance is significantly higher, it indicates that the heating element is damaged, and it is recommended to replace the heating element.
(5) Use the R1Ω range of a multimeter to measure the defrost heating fuse (65℃), which should be conductive. If it is not conductive, then it has blown and needs to be replaced with a defrost heating fuse (65℃). It is necessary to emphasize here: absolutely do not use fuses of other specifications as substitutes, and never directly short-circuit the circuit.
Fault Phenomenon: After continuous use for several days, the Ronshen frost-free refrigerator experiences a rise in internal temperature and stops cooling. If the machine is shut down for a few days and then restarted, it can operate normally again, but after a few days, the fault repeats.
Ronshen Refrigerator Cannot Cool Continuously