What is the cause of the increasing slowdown in the deheating of high and low temperature test chambers

Under normal circumstances, the high and low temperature test chamber will be set according to the time and temperature, reduce the temperature to the relative value, but it will be because the application time of the machine and equipment is too long, or the actual operation is not good, which causes the high and low temperature test chamber to reduce the temperature more and more slowly, what should be paid attention to? 1.
Observe whether the refrigeration unit can be started in the whole process of the operation of the environmental test box, and the refrigeration compressor can be started during the operation of the environmental test equipment, indicating that the household appliance route from the main switching power supply to the refrigeration compressor is normal, and there is no problem
at the software level of the household appliance system.
2, the circuit system has no problems, check the refrigeration unit
again.
First check that the exhaust pipe and respiratory working pressure of the ultra-low temperature (R23) grade refrigeration compressor of the two groups of refrigeration units are slightly lower than the standard value, and the respiratory working pressure is pumped, indicating that the amount of refrigerant in the main refrigeration unit is not enough
.
3, with the hand to touch the main generator set R23 refrigeration compressor exhaust pipe and breathing pipe, found that the temperature of the exhaust pipeline is not high, the temperature of the breathing pipe is not low (not frosted), which also shows the lack
of R23 refrigerant of the main generator set.
4.
To determine the common fault cause, the whole process of the operation of the fusion environment test chamber is deepened to determine the common fault cause, and the environmental test chamber has two refrigeration units
.
One is the dominant generator set, the other is the auxiliary generator set, when the temperature reduction speed is very large, the 2 sets of generator sets are working separately, and in the early stage of the temperature maintenance link, the 2 sets of generator sets are still working
separately.
When the temperature is basically stable, the auxiliary generator set terminates the work, and the main generator set keeps the temperature stable
.
If the main generator set R23 leaks, the actual effect of the cooling of the main generator set is not large, because in the whole process of temperature reduction, the two generator sets work separately, so there is no condition that the temperature cannot be stabilized, and the temperature reduction speed is reduced
.
In the temperature maintenance link, if the auxiliary generator set terminates the work, the main generator set has no cooling effect, the gas in the experimental box will rise slowly, when the temperature rises to the necessary level, the automatic control system will start the auxiliary generator set to reduce the temperature, reduce the temperature to the preset value of the periphery, and then the auxiliary generator set will terminate the work, so continuously, there will be abnormal conditions
.
In general, it has been determined that the cause of common failures is the leakage
of the refrigerant R23 of the ultra-low temperature (R23) class generator set of the main generator set.
The refrigeration unit was leaked to find leaks, and the leak detector and soap liquid were closely combined to check, and it was found that the stem of the heat flow bypass valve relay was cracked by about 1cm, and the relay was dismantled, and the system could be
recharged with fluorine.