1, the leakage of the refrigeration system, with a leak detector and soap and water combined method of inspection and found a hot gas bypass valve stem valve split about 1cm of the slit. Replace the solenoid valve, re-fill the system, the system is running normally. As can be seen above, the analysis and judgment of the fault phenomenon is basically easy to difficult, first "outside" after "in", the first "electrical" after the "cooling" of the context of the analysis and judgment, familiar and Understanding the principle and working process of the test chamber is the basis for analyzing the fault judgment fault.

2, did not determine the cause of the failure, combined with the control process to further confirm the cause of the failure, the test chamber has two sets of refrigeration units. One for the host group, the other for the auxiliary unit, the cooling rate is large, the two groups of units at the same time, in the early stage of the temperature to maintain the two groups still work at the same time. To stabilize the temperature initially, the auxiliary unit to stop working, by the host group to maintain the stability of the temperature. If the host group R23 leak, will make the main unit cooling effect is not, due to cooling process, the two units at the same time work, so there is no stable temperature of the phenomenon, and indicate the cooling rate. In the temperature holding stage, once the auxiliary unit stops working, the main unit has no cooling effect, the air inside the test box will slowly rise, when the temperature rises to a certain extent, the control system will start the auxiliary unit to cool down, the temperature dropped to Set value (-55 ℃) near, and then auxiliary units and stop working, so repeated, there will be shown in Figure 3, the fault phenomenon. At this point, the production failure has been confirmed because the main unit of the low temperature (R23) class unit refrigerant R23 leakage.

3, the electrical system is no problem, continue to check the refrigeration system. First check the two groups of refrigeration unit low temperature (R23) class compressor exhaust and suction pressure are lower than the normal value, and the suction pressure was evacuated, indicating that the main cooling unit of the refrigerant is insufficient. Hand touch the host group R23 compressor exhaust and suction lines and found that the exhaust pipe temperature is not high, the suction pipe temperature is not low (not frost), which also shows the host group R23 Lack of refrigerant, the system leaks fluoride.

4, because it is the temperature can not hold to observe the refrigeration compressor in the process of running the test chamber is able to start, the compressor in the process of running the test box can start, indicating from the main power supply to the compressor electrical line normal, electrical system There is no problem.

5, the test box can be cooled, indicating that external factors cooling water can be ruled out.