What are the possible reasons for the compressor of the high and low temperature test chamber not functioning to cool?
Reason for the first situation:
1. Due to the inability to maintain the temperature, observe whether the refrigeration compressor can start during the operation of the test chamber. The compressor can start normally during the operation of the environmental test equipment, indicating that the electrical circuits from the main power supply to each compressor are normal, and there are no problems with the electrical system. If there are no problems with the electrical system, continue to check the refrigeration system. First, check that the exhaust and suction pressures of the two sets of refrigeration units' low-temperature (R23) compressors are lower than the normal values, and the suction pressure is in a vacuum state, indicating that the refrigeration dosage of the main refrigeration unit is insufficient.
2. Touch the exhaust and suction pipelines of the R23 compressor of the main unit with your hand. It is found that the temperature of the exhaust pipeline is not high, and the temperature of the suction pipeline is not low (no frosting), which also indicates that the (R23) refrigerant of the main unit is lacking.
The reason for the second situation:
The cause of the fault has not been determined. Further confirmation of the fault cause is needed by combining the control process of the test chamber. The test chamber has two sets of refrigeration units. One is the main unit, and the other is the auxiliary unit. When the cooling rate is high, both units work simultaneously. In the initial stage of temperature stabilization, both units still work simultaneously. Once the temperature stabilizes initially, the auxiliary unit stops working, and the main unit maintains the temperature stability. If the R23 refrigerant of the main unit leaks, the cooling effect of the main unit will be poor. Since both units work simultaneously during the cooling process, there is no phenomenon of the temperature not being stable, but the indicated cooling rate decreases. During the temperature stabilization stage, if the auxiliary unit stops working and the main unit has no cooling effect, the air inside the test chamber will slowly rise. When the temperature rises to a certain extent, the control system will start the auxiliary unit to cool down and bring the temperature down to a value close to the set point. Then the auxiliary unit stops working, and this process repeats, resulting in the occurrence of the fault phenomenon.
At this point, it has been confirmed that the cause of the production fault is the leakage of the refrigerant R23 of the low-temperature (R23) unit of the main unit. To check for leaks in the refrigeration system, use a leak detector and soap water in combination to inspect. A thermal bypass electromagnetic valve with a cracked valve stem was found. Replace this electromagnetic valve and refill the system with refrigerant. The system operates normally.
Summary: As can be seen from the above text, the analysis and judgment of this fault phenomenon are basically in an order from easy to difficult, starting from "outside" to "inside", "electrical" to "refrigeration". Analyzing and judging in this way, familiarizing with and understanding the principle and working process of the test chamber is the basis for analyzing and diagnosing faults.
