Manitowoc Indigo Series Technician's Handbook page 177

CHECK PROCEDURE
Symptom #1 Machine is off and the display indicates
"Delay xx min, HPCO Active".
1. Cycle ice machine with the on/off button.The ice
machine will go to an initial start sequence if the
HPCO is closed. If the HPCO is open, another 60
minute delay period starts.
• Ice Machine starts - Run the system to see if the
control trips at the rated pressure. If HPCO opens
at a pressure significantly lower or higher than
the control setting of 450 psig replace the HPCO.
If the control opens at the correct pressure find
the root cause - Fan motor, dirty condenser,
refrigeration system issue, etc.
• Ice Machine Does Not Start - Continue with the
next step.
2. Leave all wiring connectors attached and perform
testing within the 60 minute time delay period.
Check for 24 volts at terminals V & C (interconnecting
wiring connections) on the ice machine control
board.
A. 24 volts - Proceed with next step
B. 0 Volts - Restore line voltage to condensing
unit, or repair interconnecting wiring, or replace
transformer in condensing unit.
3. Check for 24 volts at terminals C & HPC1.
A. 24 volts - Proceed with next step.
B. 0 volts - HPCO switch is open. Verify pressure -
Below cut-in replace HPCO - Above cut-in find
root cause problem.
4. Check for 24 volts at terminals C & HPC2.
A. 24 volts - Faulty relay on control board - Replace
control board.
B. 0 volts - HPCO switch is open. Verify pressure -
Below cut-in, replace HPCO - Above cut-in, find
root cause problem.
Part Number STH026 6/15 177