Manitowoc ICVD3095, Technician'S Handbook

Page: 214 / 350

214 Part Number Preliminary 6/11
QuietQube® Models - Harvest Valve Analysis
Symptoms of a harvest valve remaining partially open
during the freeze cycle can be similar to symptoms of
either an expansion valve or compressor problem. The
best way to diagnose a harvest valve is by using
Manitowoc’s Ice Machine Freeze Cycle Refrigeration
System Operational Analysis Table.
Use the following procedures to determine if a harvest
valve is remaining partially open during the freeze
cycle.
QUIETQUBE® REMOTE CONDENSING UNIT
MODELS HARVEST VALVE ANALYSIS
The valve can fail in two positions:
•
Valve will not open in the Harvest cycle.
• Valve remains open during the Freeze cycle.
Valve will not open in the Harvest cycle
Although the circuit board has initiated a Harvest
cycle, suction and discharge pressures remain
unchanged from the Freeze cycle. The ice machine
will remain in the Harvest cycle for 3.5 minutes (7
minutes Quad Evaporators), then initiate a new
Freeze cycle.
Valve remains open in the Freeze cycle
Symptoms of a harvest valve remaining partially open
during the Freeze cycle can be similar to symptoms of
an expansion valve, float valve or compressor
problem. Symptoms are dependent on the amount of
leakage in the Freeze cycle.
A small amount of leakage will cause increased freeze
times and an ice fill pattern that is normal.
As the amount of leakage increases, the length of the
Freeze cycle increases and the amount of ice on the
bottom of the evaporator decreases.
A small amount of leakage will cause an audible
indication as the vapor passes through the valve. As
the size of the leak increases, the audible indication
becomes more apparent.