Dust buildup on the condenser fins varies in thickness, creating distinct zones of heat exchange capability across the condenser surface. This disrupts uniform heat dissipation, directly upsetting the gas-liquid equilibrium of the refrigerant and triggering a series of chain reactions leading to malfunctions.

First, there is an imbalance in refrigerant distribution within the condenser. In areas with severe dust accumulation, heat exchange is poor, and high-temperature gaseous refrigerant cannot be sufficiently cooled and liquefied; in clean areas, cooling efficiency is high, and the refrigerant rapidly condenses into a liquid. With one side of the condenser cooling adequately while the other fails to dissipate heat sufficiently, liquid refrigerant tends to accumulate in localized areas, forming liquid pockets. This further reduces the effective heat exchange area, causing the system’s condensing pressure to drift upward continuously, and pressure fluctuations to become erratic.

Second, this triggers a disruption in the refrigerant’s gas-liquid phase balance. In some tubes, the refrigerant is insufficiently cooled and continues to flow as superheated gas, while in adjacent tubes, it has already fully condensed into a liquid. The coexistence of these two phases causes inconsistent flow resistance across the tubes; the gas and liquid flows within the condenser interfere with each other, resulting in refrigerant flow imbalance. Consequently, the compressor suction conditions become unstable, with suction temperatures fluctuating between excessively high levels and instances of liquid refrigerant return, increasing the risk of liquid slugging.

Persistently high and unstable condensing pressure directly increases the compressor’s operating load, causing the discharge temperature to rise. To maintain the evaporator side temperature, the unit continuously increases its output, resulting in frequent high-pressure protection trips and intermittent high-temperature alarms. Within the same condenser, localized overheating and overcooling occur, widening the temperature differences across the tubes and increasing thermal cycling stress at welds and elbows, which, over the long term, elevates the risk of refrigerant leaks.

At the same time, the operating conditions of the thermal expansion valve consistently deviate from the design range. Fluctuations in condensing pressure cause the subcooling of the refrigerant upstream of the valve to vary constantly, resulting in repeated imbalances in the liquid supply from the expansion valve. As the liquid supply fluctuates, heat exchange within the evaporator becomes unstable, causing simultaneous fluctuations in evaporator temperature and vacuum level. This manifests as difficulty in stabilizing the evaporator temperature and an increased likelihood of foaming and mist entrainment.

Furthermore, dust accumulation disrupts the airflow from the fan, creating turbulence. Uneven dust distribution causes airflow short-circuiting, preventing hot air from being expelled smoothly and leading to repeated localized heat buildup. The condenser’s temperature distribution continues to shift, distorting the refrigerant temperature signals collected by the transmitters. As a result, the control system continuously adjusts the heating power incorrectly, creating a vicious cycle of reduced heat dissipation → increased pressure → increased load.

Long-term uneven dust accumulation also accelerates the rise in compressor oil temperature, causing the viscosity of the lubricating oil to decrease and its lubricating performance to weaken. When the refrigerant is subjected to significant pressure fluctuations over an extended period, the stability of the oil film deteriorates, leading to increased internal wear in the compressor. In many cases, this issue is mistakenly attributed to fan failure or insufficient refrigerant. However, after thoroughly cleaning the dust from the fins, fluctuations in refrigerant pressure and high-pressure alarms are significantly alleviated.