display cases Refrigeration failures and maintenance methods (9)

dual-temperature dual-controller display cases The refrigerator compartment is not cold but can stop

[Explanation] Other forms of cooling differentials , The maintenance ideas and methods are the same as the above ordinary models. Trouble phenomenon: refrigerated showcase BCD一203 dual-temperature dual-control display cases, the freezer compartment is normal, and the refrigerating compartment is poorly refrigerated, but the automatic startup and shutdown are normal. Failure analysis: The electromagnetic two-way reversing valve is always in the position of connecting the freezing capillary tube and blocking the refrigerating capillary tube, so that the refrigerant can only flow through the freezer evaporator for refrigeration, but not through the refrigerated evaporator. Since whether the two-way solenoid valve is energized or not is determined by the refrigerating thermostat, both are included in the scope of maintenance. However, the failure rate of refrigerating thermostats is high, and the failure rate of two-way electromagnetic directional valves is extremely low. Troubleshooting: Generally, replace the refrigerated thermostat of the same model first, then replace the electrical part of the electromagnetic reversing valve, and finally replace the two-way electromagnetic reversing valve.

[Note] For the sake of insurance during maintenance, you can also use the following electric team and voltage method to diagnose the damage of the refrigeration thermostat and the electromagnetic reversing valve before replacing it. Unplug the display cases, turn on the electrical box of the two-way solenoid directional valve, plug in the display cases, and measure the voltage of the two leads of the solenoid valve. If there is AC 220V, it must be judged that there is a problem with the thermostat, otherwise there is no AC 220V voltage. There is a problem with the solenoid valve. Because the L and C terminals of the refrigeration thermostat are required to be connected under normal temperature, the electromagnetic reversing valve is de-energized, and the C and S terminals of the refrigeration thermostat are connected at low temperature, and the electromagnetic reversing valve is energized.

dual-temperature dual-controller refrigerating room frost-free operation dull failure phenomenon: refrigeration without frost. The compressor was running normally when it was turned on, but it quickly became dull, and the exhaust pipe was very hot, and the return pipe was not cold. Failure analysis: The cold storage capillary tube is dirty, which affects the flow of refrigerant and increases the load of the compressor. Troubleshooting: Plug in the display cases to make the compressor run. Which capillary tube is frosted or has a cold sensation indicates that the capillary tube is blocked. Open the capillary tube to release air, and use the display cases refrigerant flow impact to flush the dirt out of the capillary tube, and then open the compression Machine process tube, install pressure gauge, after blowing through the system with nitrogen, replace the dry filter. If the above method still cannot eliminate the fault, you can only open the refrigerating capillary tube, the compressor process tube in turn, after venting the refrigeration system, and inject nitrogen from the compressor process nozzle to blow through the refrigeration line, and then replace the dry filter. The refrigeration system is blown through, evacuated, filled with refrigerant, and sealed.

LAST：General principles for the design and layout of walk-in cooler refrigeration systems (2) NEXT：Display cooler refrigeration failures and maintenance methods (ten)