Manitowoc QR0670C Technician Manual page 144

ANALYZING DISCHARGE PRESSURE
1. Determine the ice machine operating conditions:
Air temp. entering condenser
Air temp. around ice machine
Water temp. entering sump trough
2. Refer to Cycle Times/24-Hour Ice Production/
Refrigeration Pressure Chart for ice machine being
checked.
Use the operating conditions determined in step 1
to find the published normal discharge pressures.
Freeze Cycle
Harvest Cycle
3. Perform an actual discharge pressure check.
Beginning of
Cycle
Middle of
Cycle
End of 
Cycle
4. Compare the actual discharge pressure (step 3)
with the published discharge pressure (step 2).
The discharge pressure is normal when the actual
pressure falls within the published pressure range
for the ice machine's operating conditions. It is
normal for the discharge pressure to be higher at
the beginning of the Freeze cycle (when load is
greatest), then drop throughout the Freeze cycle.
______
______
Freeze
Cycle psig
__________
__________
__________
–140–
______
______
______
Harvest
Cycle psig
__________
__________
__________