1. We have to distinguish whether the working voltage of the refrigeration compressor is firm. If the AC contactor connected to the refrigeration compressor does not pull in, the switching power supply of the high and low temperature test box cannot be based on this. There is also whether the cable of the refrigeration compressor connected to the high and low temperature test box is broken or not connected. Some high and low temperature test chambers still have some short circuit faults during the whole process of transportation. Then distinguish whether the rated operating voltage meets the requirements.
2. It is necessary for professionals to distinguish the current level of the refrigeration compressor in the high and low temperature test chamber. All current levels must be rated voltage of the refrigeration compressor before they can work normally. If the working voltage is normal, the current amount is not specified , Then it shows the lack of refrigerant.
　　 3. Observe whether the heat exhaust fan of the high and low temperature test box is in normal operation. Under working conditions, the wind frequency should be relatively stable, the wind should be uniform and the wind pipe should be accurate. There is also a way to sigh the temperature of the exhaust pipe of the refrigeration compressor. The normal temperature of the high and low temperature test chamber is higher than normal temperature, just like the temperature of the external exhaust fan of the central air conditioner is higher. Observe whether the circulating system centrifugal fan in the room is in normal operation. If it is not in operation after burning, the air conditioner evaporator cannot evaporate normally, so that the temperature cannot be reduced.