Freeze Cycle Suction Line Temperature Analysis - Manitowoc QR0670C Technician Manual

Freeze Cycle Suction Line Temperature Analysis

Suction line temperature alone cannot diagnose an ice
machine. However, comparing this temperature during
the Freeze cycle while using Manitowoc's
Refrigeration Component Analysis Chart, will help
diagnose an ice machine malfunction.
The actual temperature of the suction line varies by
model and will change throughout the Freeze cycle.
This makes documenting the "normal" suction line
temperature difficult. The key to diagnosis is observing
the suction line temperature during the last three
minutes of the Freeze cycle.
Use this procedure to document Freeze cycle suction
line temperatures.
1. Use a quality temperature meter, capable of taking
temperature readings on curved copper lines.
2. Attach the temperature meter's thermocouple to the
copper suction line within 6 in. of the suction shut-
off valve.
Do not simply insert the sensing device under the
insulation. It must be attached to and reading the
actual temperature of the copper line.
3. Monitor the suction line temperature during the last
three minutes of the Freeze cycle and record the
low event.
4. Use this with other information gathered on the
Refrigeration Component Analysis Chart to
determine the ice machine malfunction.
5. Verify refrigerant amount is correct by weight when
recovering refrigerant and replacing a TXV.
Grossly overcharged QuietQube ice machine in
ambient temperatures below 70°F will have a
suction line temperature below 10°F.
Important
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