Manitowoc QD0202A, Service Manual

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Section 7 Refrigeration System
Part No. 80-1100-3
7-11
ICE FORMATION PATTERN
Evaporator ice formation pattern analysis is helpful in ice
machine diagnostics.
Analyzing the ice formation pattern alone cannot
diagnose an ice machine malfunction. However, when
this analysis is used along with Manitowoc’s
Refrigeration System Operational Analysis Table, it can
help diagnose an ice machine malfunction.
Improper ice formation can be caused by any number of
problems.
Example: An ice formation that is “extremely thin on
outlet” could be caused by a hot water supply, a dump
valve leaking water, a faulty water fill valve, a low
refrigerant charge, etc.
1. Normal Ice Formation
Ice forms across the entire evaporator surface.
At the beginning of the freeze cycle, it may appear that
more ice is forming on the intlet of the evaporator than
on the outlet. At the end of the freeze cycle, ice
formation on the outlet will be close to, or just a bit
thinner than, ice formation on the intlet. The dimples in
the cubes at the outlet of the evaporator may be more
pronounced than those on the intlet. This is normal.
The ice thickness probe must be set to maintain the ice
bridge thickness at approximately 1/8". If ice forms
uniformly across the evaporator surface, but does not
reach 1/8" in the proper amount of time, this is still
considered normal.
2. Extremely Thin at Evaporator Outlet
There is no ice, or a considerable lack of ice formation
on the outlet of the evaporator (tubing outlet).
Examples: No ice at all on the outlet of the evaporator,
but ice forms on the intlet half of the evaporator. Or, the
ice at the outlet of the evaporator reaches 1/8" to initiate
a harvest, but the intlet of the evaporator already has
1/2" to 1" of ice formation.
Figure 7-8. Extremely Thin Ice Formation at
Evaporator Outlet
Important
Keep the water curtain in place while checking the
ice formation pattern to ensure no water is lost.
SV1576
OUTLET
INLET
ICE
ICE