Koolaire KD0172A, Руководство техника

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Part Number STH047 5/16 67
ANALYZING WHY SAFETY LIMITS MAY STOP THE ICE
MACHINE
According to the refrigeration industry, a high percentage
of compressor failure is a result of external causes. These
can include flooding or starving expansion valves, dirty
condensers, water loss to the ice machine, etc. The safety
limits protect the ice machine (primarily the compressor)
from external failures by stopping ice machine operation
before major component damage occurs.
The safety limit system is similar to a high-pressure cutout
control. It stops the ice machine, but does not tell what
is wrong. The service technician must analyze the system
to determine what caused the high-pressure cutout, or a
particular safety limit, to stop the ice machine.
The safety limits are designed to stop the ice machine
prior to major component failures, most often a minor
problem or something external to the ice machine. This
may be difficult to diagnose, as many external problems
occur intermittently.
Example: An ice machine stops intermittently on safety
limit #1 (long freeze times). The problem could be a low
ambient temperature at night, a water pressure drop; the
water is turned off one night a week, etc.
When a high-pressure cutout or a safety limit stops the
ice machine, they are doing what they are supposed
to do. That is, stopping the ice machine before a major
component failure occurs.
Refrigeration and electrical component failures may also
trip a safety limit. Eliminate all electrical components and
external causes first. If it appears that the refrigeration
system is causing the problem, use the Refrigeration
System Operational Analysis Table, along with detailed
charts, checklists, and other references to determine the
cause.