Final Analysis; Harvest Valve Leaking; Low Charge/Txv Starving - Manitowoc SD0302A Technician's Handbook

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Final Analysis

The column with the highest number of check marks
identifies the refrigeration problem.
COLUMN 1 - HARVEST VALVE LEAKING
Replace the valve as required.
COLUMN 2 - LOW CHARGE/TXV STARVING
Normally, a starving expansion valve only affects the
freeze cycle pressures, not the harvest cycle
pressures. A low refrigerant charge normally affects
both pressures. Verify the ice machine is not low on
charge before replacing an expansion valve.
1. Add refrigerant charge to verify a low charge (air
and water self-contained only). Do not add more
than 30% of nameplate refrigerant charge. If the
problem is corrected, the ice machine is low on
charge.
*Do not add charge to remotes. The symptoms of
a remote low on charge will result in a safety limit
#1 in cool ambient temperatures. Check the liquid
line temperature at the ice machine. The liquid
line will be hot with a normal or below normal
head pressure in freeze when the ice machine is
low on refrigerant.
2. Find the refrigerant leak. The ice machine must
operate with the nameplate charge. If the leak
cannot be found, proper refrigerant procedures
must still be followed Change the liquid line drier.
Then, evacuate and weigh in the proper charge.
3. If the problem is not corrected by adding charge,
the expansion valve is faulty.
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Part Number 80-1479-3 7/10