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Common Faults and Characteristics of Multi-split Air Conditioning Systems in Clean Workshops
2025/11/12
01 The working principle of multi-split systems
The indoor temperature sensor controls the electronic expansion valve on the refrigerant pipeline of the indoor unit. By changing the pressure of the refrigerant, it can perform variable frequency speed control on the refrigeration compressor of the outdoor unit or adjust the number of operating compressors, the number of working cylinders, the opening degree of the throttle valve, etc., to change the refrigeration flow of the system, achieving the purpose of adjusting the cooling or heating capacity according to the load changes in both cooling and heating modes.
02 Features of Multi-split Systems
Remarkable energy-saving effect: The multi-split system can automatically adjust the compressor speed and change the refrigerant flow rate according to the changes in system load, ensuring that the unit operates at a high efficiency. When operating at partial load, energy consumption decreases and the annual operating cost drops.
Comparison of energy efficiency among different air conditioning systems
Save building space: The air-cooled outdoor units used in multi-split systems are generally installed on the roof and do not occupy building area. The connection pipes of a multi-split system only include refrigerant pipes and condensate pipes. Moreover, the layout of the refrigerant pipes is flexible. Compared with a water system, under the condition of meeting the same indoor ceiling height, the adoption of a multi-split system can reduce the building's floor height and lower the construction cost.
Convenient for construction and installation, reliable operation: Compared with centralized air conditioning water systems, multi-split systems require much less construction work, have a shorter construction period, and are very suitable for household situations. The system has fewer links and is safe and reliable in operation and management.
Meet the usage requirements of rooms under different working conditions: The multi-split system is convenient and flexible to combine. The system can be organized according to different usage requirements to meet the usage requirements of rooms under different working conditions. For a heat recovery multi-split system, within one system, while some indoor units are cooling, others can operate for heating. In winter, the multi-split system can provide cooling for the inner zone and heating for the outer zone, transferring the heat from the inner zone to the outer zone, making full use of energy, reducing energy consumption, and meeting the air conditioning requirements of different areas.
The air conditioner is not working
There are many reasons why an air conditioner doesn't work. When the air conditioner stops working, we can first check the following items.
Could it be that the power is off?
Is the remote control broken?
Is the working parameter setting incorrect?
Is there electromagnetic interference near the indoor unit that prevents it from receiving signals correctly?
2. The air conditioning system does not heat
The common reason why the air conditioning system does not heat is: gas leakage through the four-way valve, that is, the refrigerant in the four-way valve enters the exhaust pipe. Gas leakage through the four-way valve will cause the pressure and temperature entering the low-pressure end and the compressor to rise. The increase in suction pressure will increase the load on the compressor, raise the operating current, and the high-pressure pressure and exhaust temperature after compression will be higher than the normal values.
There are errors in the connection or wiring of the low-pressure pressure sensor, or the characteristic values are abnormal. The equipment cannot perform the correct action based on the parameters.
3. Some rooms are alternately hot and cold
The phenomenon of sudden temperature changes occurs due to unstable cold capacity delivery. The possible reasons for the unstable cold capacity could be:
The refrigerant in the pipe is insufficient, which cannot meet the cooling demand of the room.
There is air inside the pipe, and the refrigerant does not flow smoothly inside the pipe, with the flow rate fluctuating between large and small.
The refrigerant distributor is damaged and cannot normally distribute the refrigerant volume to each room.
4. The room temperature fails to meet the design requirements
The room may fail to reach the designed temperature due to the excessively high exhaust temperature of the outdoor unit, causing a protective shutdown. The reasons for excessively high exhaust temperature are:
The indoor load is too small. If the indoor load is too small, the suction pressure of the compressor will be too high, thereby causing the exhaust temperature after compression to be higher than the set value.
Refrigerant shortage.
The pipes are clogged and the indoor unit filter is clogged.
The compressor is short of lubricating oil.
The presence of air in the pipe indicates unstable refrigerant quantity.
5. Nitrogen filling for pressure maintenance is due to unstable pressure
During the pressure-holding process, if the pressure is unstable, there are mainly two situations that can cause this problem
Leakage occurred at the pipe connection due to welding quality issues. This situation can be detected and resolved during the pressure-holding stage of the pipeline system.
The indoor and outdoor units are leaking. The internal leakage of the indoor and outdoor units can only be detected when the entire air conditioning system is under pressure. This requires an inspection of the outdoor unit's condenser and other connection points. For the indoor unit, a thorough elimination check should be carried out one by one. This situation consumes a considerable amount of human and material resources.
