Welbilt Manitowoc NEO UDP0080A, Technician'S Handbook

Page: 125 / 180

Part Number STH098 06/19 125
FLOODING EXPANSION VALVE SYMPTOMS
A flooding expansion valve will have discharge and suction
line temperatures 20°F (-7°C) lower than normal freeze
cycle temperatures. Normal suction line temperature and
low discharge line temperature DO NOT verify a flooding
valve. Both discharge line temperature and suction line
temperature must be low to verify a flooding expansion
valve. Ice fill pattern is thin on the left hand side of the
evaporator.
STARVING EXPANSION VALVE/LOW REFRIGERANT
CHARGE SYMPTOMS
A. Ice Fill Pattern
• Thin on top two rows of the evaporator
• Thin on entire left side of the evaporator
• Thick on the bottom of the evaporator
B. Freeze time longer than normal
• A failed TXV or low refrigerant charge will have a
suction line temperature higher than normal and a
discharge line temperature lower than normal.
• An failed TXV will not effect the discharge line
temperature during the harvest cycle. A low freeze
and discharge line temperature in the freeze cycle with
a normal harvest cycle discharge line temperature
indicates a failed TXV.
• Low refrigerant charge will have both the suction and
discharge line temperatures lower than normal in the
freeze and harvest cycles.
Diagnosis can be confirmed by installing a temporary
access valve and adding 60 grams of refrigerant: If the
suction line temperature drops or the ice fill pattern on the
top two rows fills in, the ice machine is low on refrigerant.
Refer to charging procedures for access valve installation/
removal procedure.