6-5
Section 6
Service
HARVEST HEATER ELEMENT
THERMOSTAT
Function
Safety control which de-energizes the harvest
heater contactor coil, when the evaporator
temperature exceeds the control setpoint.
The harvest heater thermostat is normally closed
and opens on an increase in temperature.
Specifications
Automatic reset
Cut-in 110°F (+/- 5°F) (thermostat closed).
Cut-out 125°F (+/- 5°F) (thermostat open).
Check Procedure
1.
Insert a temperature probe next to the harvest
heater thermostat sensor.
2.
Hook a voltmeter in parallel (across) the
harvest heater thermostat control, leaving
wires attached
3.
Cycle the ice machine into a harvest cycle by
placing a jumper wire from the ice thickness
probe to ground (see page 6-13).
4.
Temperature below listed specification:
Meter will read 0 volts and the heater
contactor coil will be energized.
Temperature above listed specification:
Meter will read line voltage and the heater
contactor coil will be de-energized.
Replace the control if:
1.
The control does not open at the specified
setpoint.
2.
The control will not reset
LOW PRESSURE CUT-OUT CONTROL
Function
Energizes and de-energizes the compressor
contactor coil.
The LPC opens when the suction pressure reaches
the cut-out setpoint, and closes when the suction
pressures reach’s the cut-in setpoint.
Specifications
Adjustable cut-in and cut-out
Factory Setting Cut-in 25 psig Cut-out 3 psig
(These are minimum setpoints. The cut-in can be
increased when low ambient temperatures will not
be experienced.)
Check Procedure
NOTE: The suction pressure must exceed the cut-
in setpoint to close the switch. The switch will
then remain closed until the suction pressure drops
below the cut-out setpoint.
1.
Attach an accurate gauge to the suction service
port on the condensing unit.
2.
Hook a voltmeter in parallel across the low-
pressure control, leaving wires attached.
3.
Front seat (close) the suction service valve on
the condensing unit. The suction pressure will
decrease causing the low-pressure control to
open at the listed specification. The voltage
reading across the low-pressure cut-out control
must be “line voltage”.
4.
Back seat (open) the suction service valve on
the condensing unit. The suction pressure will
increase causing the low-pressure control to
close at the listed specification. The voltage
reading across the low pressure cut-out control
must be “0 volts”.
5.
Replace the low pressure cut-out control when
it does not open and close properly or does not
maintain proper settings.
CAUTION
Never set the Low Pressure Control to allow the
refrigeration system to enter a vacuum.
IMPORTANT:
This test must be completed within 5 1/2
minutes of starting the harvest sequence.
Summary of Contents for P Series
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