Service manual

Refrigeration System Section 7
7-18
Part No. 80-1206-3
ANALYZING FREEZE CYCLE SUCTION LINE
TEMPERATURE
Suction line temperature cannot diagnose an ice
machine. However, comparing this temperature during
the freeze cycle, along with using Manitowoc’s
Refrigeration System Operational Analysis Table, can
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 the diagnosis is
observing the compressor 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 thermocouple to the
copper suction line within 6” of the shut-off valves.
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
Do not simply insert the sensing device under the
insulation. It must be attached to and reading the
actual temperature of the copper line.
______________
Inlet Temperature
______________
Outlet Temperature
_______________
Difference
Must be within 7°F at 5
minutes into freeze cycle