WD_2021

RED DOT UNITS

71R SERIES

71RSERIES Switches&Controls Electrical&Refrigerant Did You Know…

SWITCHES

Service Tip The most common expansion valve failure mode is due to valve charge head leaks. System contaminants lodged in valve inlet orifice may also affect valve metering and flow capabilities. Suspected metering inconsistencies many times have distinct characteristics.

 Starving Expansion Valve: Frost present on inlet of evaporator.  Flooding Expansion Valve: Hissing at valve upon system shutdown. A manifold gauge set must be installed to confirm irregular system pressures.

The EXPANSION VALVE meters refrigerant based upon evaporator heat loads. As the refrigerant gas leaving the evaporator passes through the valve’s outlet port, gas temperature is sensed by the valve’s internal sensing bulb and the refrigerant level is regulated.

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