Motak PKM0335, Service Manual

Page: 83 / 132

Part Number: 000016427 Rev 00 08/2020 83
Troubleshooting
Procedure
Step
1. Determine the ice machine operating conditions.
Example:
Air temp. entering condenser: 90°F/32.2°C
Air temp. around ice machine: 80°F/26.7°C
Water temp. entering water fill valve: 70°F/21.1°C
2A. Refer to “Cycle Time” and “Operating Pressure” charts for ice machine model being
checked. Using operating conditions from Step 1, determine published freeze cycle time
and published freeze cycle suction pressure.
Example:
Published freeze cycle time: 14.8 - 15.9 minutes
Published freeze cycle suction pressure: 65 - 26 psig
2B. Compare the published freeze cycle time and published freeze cycle suction pressure.
Develop a chart.
Example:
Published Freeze Cycle Time (minutes)
1 2 4 7 10 12 14
| | | | | | |
65 55 47 39 34 30 26
Published Freeze Cycle Suction Pressure (psig)
In the example, the proper suction pressure should be approximately 39 psig at 7
minutes; 30 psig at 12 minutes; etc.
3. Perform an actual suction pressure check at the beginning, middle and end of the
freeze cycle. Note the times at which the readings are taken.
Example:
Manifold gauge set was connected to the example ice machine and suction pressure
readings taken as follows: ________ PSIG
Beginning of freeze cycle: 79 (at 1 min.)
Middle of freeze cycle: 48 (at 7 min.)
End of freeze cycle: 40 (at 14 min.)
4. Compare the actual freeze cycle suction pressure (Step 3) to the published freeze cycle
time and pressure comparison (Step 2B). Determine if the suction pressure is high, low or
acceptable.
Example:
In this example, the suction pressure is considered high throughout the freeze cycle. It
should have been:
Approximately 65 psig (at 1 minute) – not 79
Approximately 39 psig (at 7 minutes) – not 48
Approximately 26 psig (at 14 minutes) – not 40