Pressure Control Specifications And Diagnostics; Fan Cycle Control; High Pressure Cut-Out (Hpco) Control - Manitowoc S Service Manual

Section 7
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)
S300 / S320
250 psig ±5
S420 / S450
1723 kPa ±34
S500 / S600
17.23 Bar ±.34
S850
S1000 / S1200
275 psig ±5
1896 kPa ±34
S1400 / S1600
18.96 Bar ±.34
S1800
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:
above cut-in
below cut-out line voltage
Part Number 80-1480-3
Cut-Out (Open)
200 psig ±5
1517 kPa ±34
1517 Bar ±.34
225 psig ±5
1551 kPa ±34
15.51 Bar ±.34
Fan Should Be:
0 volts running
off

HIGH PRESSURE CUT-OUT (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 (3103 kPa ±69, 31 Bar ±.69)
Cut-in: Manual or automatic reset
Must be below 300 psig (2068 kPa, 20.68
Bar ±.69) to reset
Check Procedure
1. Set ICE/OFF/CLEAN switch to OFF.
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.
If discharge pressure exceeds 460 psig (2068 kPa,
20.68 Bar ) 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 (2068 kPa, 20.68 Bar )]
• Does not open at the specified cut-out point
Refrigeration System
! Warning
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