Manitowoc Indigo Series Technician's Handbook page 144

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® 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 dual
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 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.
144 Part Number STH026 6/15