Manitowoc J-1300, Service Manual

Page: 135 / 165

Section 7 Refrigeration System
7-30
Pressure Control Specifications and Diagnostics
FAN CYCLE CONTROL
(Self-Contained Air-Cooled Models Only)
Function
Cycles the fan motor on and off to maintain proper
operating discharge pressure.
The fan cycle control closes on an increase, and
opens on a decrease in discharge pressure.
Specifications
Model Cut-In (Close) Cut-Out (Open)
J200 J250
J320 J420
J450 J600
250 psig ± 5 200 psig ± 5
J800 J1000
J1300 J1800 275 psig
±
5 225 psig
±
5
Check Procedure
1. Verify fan motor windings are not open or
grounded, and fan spins freely.
2. Connect manifold gauges to ice machine.
3. Hook voltmeter in parallel across the fan cycle
control, leaving wires attached.
4. Refer to chart below.
At:
Reading Should
Be:
Fan Should
Be:
above cut-in 0 volts running
below cut-out line voltage off
HIGH PRESSURE CUTOUT
(HPCO) CONTROL
Function
Stops the ice machine if subjected to excessive high-
side pressure.
The HPCO control is normally closed, and opens on a
rise in discharge pressure.
Specifications
Cut-out: 450 psig
±
10
Cut-in: Manual (below 300 psig to reset)
Check Procedure
1. Set ICE/OFF/CLEAN switch to OFF, and reset
HPCO if tripped.
2. Connect manifold gauges.
3. Hook voltmeter in parallel across the HPCO,
leaving wires attached.
4. On water-cooled models, close the water service
valve to the water condenser inlet. On self-
contained air-cooled and remote models,
disconnect the fan motor.
5. Set ICE/OFF/CLEAN switch to ICE.
6. No water or air flowing through the condenser
will cause the HPCO control to open because of
excessive pressure. Watch the pressure gauge and
record the cut-out pressure.
WARNING
If discharge pressure exceeds 460 psig and the
HPCO control does not cut out, set
ICE/OFF/CLEAN switch to OFF to stop ice
machine operation.
Replace the HPCO control if it:
•
Will not reset (below 300 psig)
•
Does not open at the specified cut-out point