Moisture in the Cooling System

[gravata]Learn how it works and ways to combat it. [/gravata] Often moisture causes disturbances in the cooling system generating negative impacts both for the compressor as well as for the refrigerator. Preventing it and combating it are tasks that all contractors must be prepared to handle. First, let’s understand the most common ways moisture enters the cooling system and what we can do to prevent this from happening. The moisture present in air is a contaminant that can enter the system through cracks, tubing line ruptures, micro holes which allow air to enter the circuit (and along with it, moisture). Umidade-no-Sistema-de-Refrigeração-1

However, moisture may also come from the assembly process or from cooling system maintenance. The table shows how this happens and ways to fix the problem. For systems contaminated with moisture, compressor replacement is recommended rather than just changing the lubricant oil. When the compressor operates in the presence of moisture, lubricant oil degradation takes place, making it dark and smelly, along with changing its density and function. Therefore, the oil loses its lubricity performance and becomes acid, causing increased compressor wear, reducing its useful life. Some common effects of moisture in the compressor and cooling system include:


Weakening of suction / discharge valves, may cause them to rupture.

  • Deterioration of system performance caused by the presence of fluid in the lines, which hinders heat exchange in the evaporator and gas expansion;
  • Increase in electric energy consumption by oil lubricity performance loss and tubing blockage, causing the compressor to work for longer periods.

Carbonization and degradation of metal parts and oil.


Electric motor short circuit due to the coils’ insulation degradation.


Carbonização e degradação de partes metálicas e do óleo.

Important: before replacing the compressor, it’s necessary to identify the cause of the moisture problem, as explained above. If in doubt, see the table. Umidade-no-Sistema-de-Refrigeração-2-OK

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