High temperature problems and overload protection investigation of central air conditioning module exhaust

In central air conditioning systems, module machines are widely used with their efficient and flexible characteristics. However, the protection shutdown caused by excessive exhaust temperature has always been a key pain point in the operation and maintenance process. This article will thoroughly analyze the hazard mechanisms, core incentives of exhaust gas high temperatures, and the inspection methods for overload protection of compressors in refrigeration and heating modes.

Hazard mechanism of high exhaust temperature

Excessive compressor exhaust temperature can cause a series of serious consequences. High temperatures will destroy the oil film of the lubricant, accelerate bearing wear, and lead to carbonization of the lubricant; cause the motor insulation to age, the winding temperature exceeds the limit, and increase the risk of short circuit; prompt the refrigerant to decompose, and produce acidic substances to corrode the pipeline; it will also overload the thermal stress of the exhaust valve group, causing the valve plate to be fatigued and broken.

The built-in temperature sensor of the module compressor system will monitor the exhaust temperature in real time. Once the limit value is continuously detected, the protection shutdown will be triggered and an error code will be reported. If the high temperature exhaust gas is not handled correctly in time, the compressor may be damaged.

Four core incentives for high exhaust temperature

Refrigerant leak or insufficient

When the system refrigerant leaks or is insufficient, the compressor cannot obtain sufficient cooling during operation and the exhaust temperature will be too high. This not only triggers the system's high temperature protection mechanism, but also causes wear and damage to the compressor mechanical components in severe cases.

Thermal expansion valve is blocked

The thermal expansion valve is responsible for regulating the flow of refrigerant into the evaporator. If the valve is blocked, the amount of refrigerant entering the evaporator decreases, the compressor suction pressure drops, and the exhaust temperature increases. At this time, the expansion valve needs to be cleaned or replaced in time.

The filter is dirty and blocked

The function of the filter is to filter impurities in the system to prevent them from entering key components such as compressors. Once the filter is blocked, it will affect the normal circulation of the refrigerant, resulting in insufficient suction pressure of the compressor and excessive exhaust temperature. Regular inspection and cleaning or replacement of filters can effectively prevent this problem.

Electronic expansion valve blocked

The electronic expansion valve also controls the flow of refrigerant. If it is blocked, the flow of refrigerant will decrease, which will affect the normal operation of the compressor and cause the exhaust temperature to rise. In this case, the working status of the electronic expansion valve needs to be checked and necessary repairs or replacements are carried out.

Compressor overload protection check

Compressor overload protection is divided into cooling mode and heating mode. The following are the inspection methods.

Compressor overload protection check in refrigeration mode

Check whether the ambient temperature or water temperature is abnormal

Check the local ambient temperature to confirm whether it is abnormally high.

Pay attention to the water temperature in and out of the shell and tube. If the use requirements specified in the instructions are exceeded, measures should be taken to lower the water temperature.

Check whether the exhaust temperature of the system is normal

Check the unit's exhaust temperature. If it is too high, a pressure gauge must be connected to the system. If the saturation temperature corresponding to the pressure value in the system is consistent with the current ambient temperature, it means that the refrigerant in the system is normal; if the pressure value in the system is close to atmospheric pressure, or the saturation temperature corresponding to the measured pressure value is more than 10 degrees lower than the current ambient temperature, it means that the system refrigerant is insufficient and the system leakage point needs to be checked (the test must be carried out for more than 1 hour after the unit is shut down).

Check whether the system fins are dirty and blocked. If they are very dirty, they need to be cleaned in time.

Observe the exhaust temperature and unit current. If the exhaust temperature is below 55℃, use a multimeter to measure the unit current immediately. If the current is much larger than the current marked by the nameplate, it means that the unit is infused with too much refrigerant. In addition, if the compressor is overloaded and damaged due to liquid strikes, it will also be accompanied by an abnormal noise of "click". This situation often occurs when the newly replaced compressor or the unit is turned on without preheating.

Check whether the operating voltage exceeds the manual requirements

Use a multimeter to measure the unit input voltage to ensure that the voltage does not exceed the range of use specified in the instruction manual (±10% of the rated voltage).

Shanghai KUB Refrigeration Equipment Co., Ltd.

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