Service Manual

Part Number: 000015431 Rev 02 6/20 111
Analyzing Suction Pressure
The suction pressure gradually drops throughout the
freeze cycle. The actual suction pressure (and drop rate)
changes as the air and water temperature entering the
ice machine changes. These variables also determine the
freeze cycle times.
To analyze and identify the proper suction pressure drop
throughout the freeze cycle, compare the published
suction pressure to the published freeze cycle time.
NOTE: Analyze discharge pressure before analyzing suction
pressure. High or low discharge pressure may be causing
high or low suction 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 Operating Pressure table (starting on page
183) 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 suction pressure check.
Freeze Cycle psig (kPa)
1 Minute into the Freeze Cycle
Middle of Freeze Cycle
End of Freeze Cycle
4. Compare the actual suction pressure (step 3) with the
published suction pressure (step 2).
NOTE: The suction 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 suction pressure to be higher at the beginning of the
Freeze cycle (when load is greatest), then drop throughout
the Freeze cycle.