Refrigeration Components; Refrigerant Charge Verification - Manitowoc QuietQube SD0672C Technician's Handbook

Refrigeration Components

REFRIGERANT CHARGE VERIFICATION

QuietQube remote ice machines require the correct
amount of refrigerant (name plate charge) to operate
correctly at all ambient conditions.
An ice machine with an overcharge or undercharge of
refrigerant may function properly at higher ambient
temperatures and fails at lower ambient temperatures.
Symptoms of incorrect refrigerant amount are:
• Works during the day and malfunctions at night,
and/or fails whenever the outdoor temperature
drops.
• A Safety limit is stored in control board memory.
Refrigerant loss and ambient temperature are directly
related to each other. As the ambient temperature
drops, more refrigerant is stored in the condenser.
When the refrigerant charge and ambient temperature
create an undercharge of refrigerant in the freeze
cycle, the receiver dip tube will lose it's liquid seal.
Without liquid refrigerant to the TXV, the ice machine
fails to make a full sheet of ice in 60 minutes and a
safety limit #1 results.
When the refrigerant charge and ambient temperature
create a marginal undercharge of refrigerant, the ice
machine will be able to make a full sheet of ice, but
fails in the harvest cycle and a safety limit #2 results.
NOTE: Depending on the amount of refrigerant loss
and ambient temperature, the ice machine may
harvest for one or two cycles when restarted after an
"Automatic Shut-off" (ice machine pumped down and
shut off on low pressure control).
When refrigerant charge is suspected, verify by
recovering the refrigerant, weighing and comparing to
the nameplate amount. Refer to Refrigerant Recovery/
Evacuation" page 218 for recovery procedures.
204 Part Number 80-1505-3 6/11