Moisture in the refrigeration system can cause which of the following?

• A. Metering device freeze-up
• B. Improved energy efficiency
• C. No effect
• D. Higher COP

Answer: (A)

Moisture in the refrigerant loop can freeze in the metering device, blocking the tiny passage that controls how much refrigerant enters the evaporator. As the refrigerant passes through the metering device, pressure drops and temperatures fall; any entrained water turns to ice at this point and wedges in the orifice or valve. That ice restricts or stops the flow of refrigerant, starving the evaporator of liquid needed for proper heat absorption. The result is poor cooling, frost or ice buildup on nearby components, and potential strain on the compressor from improper refrigerant flow. Because moisture causes this blockage, it does not improve efficiency, nor does it leave the system unaffected or increase COP.