this OEM defrost control board manages the transition between heating and defrost modes by monitoring the nominal initiation temperature of 28°F and terminating the cycle once the coil reaches 55°F

Note that this specific model is provided without the solenoid coil

ensuring consistent performance in high-cycle environments

It requires a constant 120V signal to close the valve and stop the flow

Nordyne 664850R Service Valve 320788-704 this OEM defrost control boardThe Nordyne 664850R Service Valve is a critical component for maintaining system integrity in residential and light commercial HVAC applications. This 3 8" liquid line refrigerant valve is designed for high pressure performance, featuring a durable brass body that ensures a leak proof connection in split system air conditioners and heat pump units. As a direct OEM replacement part, the 664850R facilitates precise refrigerant management during