Ice-O-Matic VRC - Manual (Page 11)

Remote Condenser Component Description
Page 5
Mixing Valve (Headmaster, Low Ambient Control Valve)
This valve serves as the head pressure regulating valve. It contains a pre-determined charge of nitrogen in
the valve bellows. When the temperature at the condenser is above 70°F (21°C), the refrigerant flow from
the compressor is directed by the mixing valve through the condenser and into the receiver. When the
temperature at the condenser drops below 70°F (21°C), the pressure in the bellows of the mixing valve
becomes greater than the pressure of the liquid refrigerant
coming from the condenser.
This change allows the valve to partially restrict the flow of
refrigerant leaving the condenser and allows discharge gas
to by-pass the condenser and flow directly into the receiver,
mixing with the liquid refrigerant from the condenser. The
amount of discharge gas that bypasses the condenser
increases as the ambient temperature decreases.
This action of the mixing valve allows the discharge
pressure to be maintained at approximately 217 psi during
low ambient conditions. If the refrigerant system is
undercharged and the ambient temperature is below 70°F
(21°C), the mixing valve will not work properly. The mixing
valve will allow too much refrigerant to bypass the
condenser.
Receiver
The quantity of liquid refrigerant in the receiver will vary with the temperature at the condenser
coil.
Liquid Line Solenoid and Pump Down Low Pressure Control
When the bin is full or the ON-OFF switch is turned to the OFF position, the liquid line
solenoid valve closes and the system begins to pump down. When the low pressure
reaches 10-20 psi, the pump down low pressure control opens and the contactor shuts
the machine off.
As the ice is removed from the bin or the ON-OFF switch is turned to the ON position, the
liquid line solenoid valve opens and the high side and low side pressures begin to equalize.
When the low side pressure reaches 50-75 psi, the pump down low pressure control closes and
the machine begins a freeze cycle.
When the machine is off for extended periods of time (either a full bin or the ON-OFF switch in
the OFF position), it will pump down approximately once every hour. This is due to the
equalization of pressures during the off cycle resetting the pump down low pressure control. It is
a normal function of the refrigeration system.
Condenser Fan Motor
The condenser fan motor is a single speed, permanent split capacitor motor and should be wired
according to the wiring diagram. The motor is permanently lubricated for long service life.