Fault analysis and maintenance: unplug the walk-in cooler power plug, use a multimeter R× lk block to detect the resistance of the three windings of the compressor, which is within the normal range. Then turn on the walk-in cooler power supply and measure the two power input wires of the relay on the electronic control board with the AC gear of the multimeter. There is no voltage. It can be seen that the compressor cannot start because the working voltage is not obtained. Following the inspection of the power supply line of the walk-in cooler, it was found that the internal fuse of the protection element TNT801 was blown, and one of the two anti-interference diodes was broken down, so the compressor did not start.

　　 TNT801 is a special component that combines two diodes and a 1.SA fuse. General repair shops do not have this accessory. According to the function of the walk-in cooler component in the circuit, two diodes 2CP23 and a 1.SA fuse can be welded together. After the test machine, the walk-in cooler will resume normal operation.

　　 first check whether the overheat protector is open. Even if the compressor motor coil is slightly short-circuited, the thermal protector will periodically trip until it is burnt out and damaged. The open circuit of the walk-in cooler thermal protector is mainly due to the fuse of the heating wire or the poor performance of the bimetal. When checking, the resistance between the pins can be measured with a multimeter. The normal resistance is several ohms.

　　Secondly, check whether the fuse of the temperature control board is blown, whether the pressure sensitive element is broken, and whether the operation board plug-in contact is good, etc. If there is no walk-in cooler problem found in the above inspection, you can focus on the temperature sensor. When the resistance value of the temperature sensor increases or is open, the compressor will not start.

　　The temperature sensor is installed under the evaporator in the refrigerator compartment. When checking the performance of the walk-in cooler temperature sensor, the temperature sensor can be placed in water with a temperature of 30C. Its resistance is about 2. Vegetable Q, if placed at a temperature of 0. In C water, its resistance is about 7.8kQ. In actual maintenance, there are often two reasons for the damage of the temperature sensor: one is that the pins or lead wires of the temperature sensor are not soldered and need to be re-soldered; the other is that the walk-in cooler sensor is not well sealed, and water seeps into it. The sensor characteristics change.

　　 When the walk-in cooler sensor has an open elbow, it means that the compressor cannot be turned on. When water seeps into the sensor, it means that the compressor does not stop. When the freezer compartment sensor is open, the freezer compartment begins to defrost and the defrosting process cannot stop automatically until the temperature fuse is blown.