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Why does the compressor overheat in the refrigerating room, and how does the evaporator and condenser affect the compressor?

  • Release time: 2026-09-02

Why does the compressor overheat in the refrigerating room, and how does the evaporator and condenser affect the compressor?

Compressor overheating is a common fault in industrial refrigeration equipment, and its origin is often related to the fault of evaporator or air-cooled condenser.

Reheat is the difference between the refrigerant gas temperature at the evaporator outlet and the saturated evaporation temperature. The recommended values for installing DL, DD and DJ coolers range from 5 K to 7 K.. When the value exceeds 12K, it is considered as overheating, which will increase the temperature of the compressor head and accelerate mechanical wear.

A common reason is that the size of FNH,FNV or FNVT capacitors is incorrect or dirty. If the condenser coil is covered with dust, the condensation pressure rises significantly. This high pressure changes the refrigerant flow through the expansion valve and produces very hot gas at the inlet of the compressor. In severe cases, the compressor discharge temperature can exceed 110 C.

Another common source is located in the evaporator. When the blades of DL,DD or DJ air coolers are blocked by accumulated frost, the heat exchange decreases sharply. The refrigerant will not absorb enough heat in the evaporator and reach the compressor in a very hot gas state. This happens when improper blade separation is selected for the working temperature of the camera.

Improper adjustment of expansion valve is another common reason. If the valve is closed too tightly, little refrigerant will circulate through the evaporator, resulting in overheating. Many technicians try to solve the symptoms without analyzing the whole circuit, and adjust the valves without checking the cleanliness of the evaporator and condenser in advance.

Lack of charging of R404A or R507A refrigerant can also lead to this phenomenon. In the case of a small amount of fluid, the refrigerant will soon evaporate completely in the evaporator and continue to be heated by the air flow in the chamber. In this case, it can also be observed that the overall cooling capacity of the facility decreases and it takes a long time to reach the target room temperature.

The consequences of keeping the compressor overheated are serious. Compressor lubricating oil degrades at high temperature and loses its lubricating performance. This shortens the service life of the compressor by 40% to 60%. In extreme cases, the compressor completely fails and the maintenance cost is very high.

The correct diagnostic procedure starts with checking the state of the condenser: cleanliness, airflow, installation distance and no hot air recirculation. Then check the evaporator: fin status, frost accumulation, thawing system operation. Only when both components are in the correct state can the expansion valve and refrigerant load be checked and adjusted.

Don't forget to check the dimension safety margin in the old project. With the passage of time, the heat load conditions may change, and in the summer when the temperature rises, the condenser that performs well at the source may become insufficient.

FAQ
What is the recommended temperature rise value of DL, DD and DJ evaporators? The optimal range of these devices is 5 K to 7 k.
What happens if the compressor discharge temperature exceeds 110°C? The service life of the compressor is greatly shortened due to the degradation of lubricating oil.
Will dirty capacitors lead to excessive overheating? Yes, fouling will increase the condensation pressure and make the cooling cycle out of balance.
What happens if frost accumulates on the wings of the evaporator? It reduces heat exchange and causes hot gas to enter the compressor.
Should I adjust the expansion valve when it is overheated first? No, before touching the valve, first check the state of the condenser and evaporator.
Does lack of refrigerant lead to overheating? Yes, insufficient load is one of the most common reasons in actual installation.

Integrated keywords: overheating, refrigeration compressor, FNH air condenser, FNV air condenser, FNVT air condenser, DL series air cooler, DD series air cooler, DJ series air cooler, expansion valve, R404A,R507A.

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