Scotsman NM650R Service Manual page 21

OPERATION: Refrigeration
The refrigeration system under low condenser
air temperatures is much the same as it is
under higher temperatures, with the exception
that the resulting low head pressures cause
the head pressure control to close off the
liquid line between ththe condenser and the
receiver. This forces more refrigerant into the
DISCHARGE
LINE
HEAD
PRESSURE
CONTROL
VALVE
Low Condensing Temperature
Refrigeration Schematic
LIQUID LINE
KING
VALVE
RECEIVER
December, 1988
condenser (with a small amount of discharge
gas going into the receiver to maintain
pressure until the head pressure is built back
up to the rated gauge pressure of 220 psig).
At that pressure the valve opens up the liquid
line from the condenser to the receiver.
DETAIL OF HEAD
PRESSURE CONTROL
VALVE
LIQUID LINE
VALVE
SUCTION
LINE
COMPRESSOR
Page 21
NM650R
REMOTE CONDENSER
THERMOSTATIC
EXPANSION
VALVE
EVAPORATOR