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Refrigeration System
HOW TO USE THE REFRIGERATION SYSTEM OPERATIONAL ANALYSIS TABLES
General
These tables must be used with charts, checklists
and other references to eliminate refrigeration
components not listed on the tables and external
items and problems which can cause good
refrigeration components to appear defective.
The tables list five different defects that may affect
the ice machine’s operation.
NOTE: A low-on-charge ice machine and a starving
expansion valve have very similar characteristics
and are listed under the same column.
NOTE: Before starting, see “Before Beginning
Service" for a few questions to ask when talking to
the ice machine owner.
Procedure
Step 1
Complete the “Operation Analysis” column.
Read down the left “Operational Analysis” column.
Perform all procedures and check all information
listed. Each item in this column has supporting
reference material to help analyze each step.
While analyzing each item separately, you may find
an “external problem” causing a good refrigerant
component to appear bad. Correct problems as they
are found. If the operational problem is found, it is
not necessary to complete the remaining
procedures.
Step 2
Enter check marks in the small boxes.
Each time the actual findings of an item in the
“Operational Analysis” column matches the
published findings on the table, enter a check mark.
Example: Freeze cycle suction pressure is
determined to be low. Enter a check mark in the
“low” box.
Step 3
Add the check marks listed under each of
the four columns. Note the column number with the
highest total and proceed to “Final Analysis.”
NOTE: If two columns have matching high
numbers, a procedure was not performed properly
and/or supporting material was not analyzed
correctly.
Final Analysis
The column with the highest number of check
marks identifies the refrigeration problem.
COLUMN 1 - HOT GAS VALVE LEAKING
Normally, a leaking hot gas valve can be repaired
with a rebuild kit instead of changing the entire
valve. Rebuild or replace the valve as required.
COLUMN 2 - LOW CHARGE/TXV STARVING
Normally, a starving expansion valve only affects
the freeze cycle pressures, not the harvest cycle
pressures. A low refrigerant charge normally affects
both pressures. Verify the ice machine is not low on
charge before replacing an expansion valve.
1.
Add refrigerant charge in 2 to 4 oz. increments
as a diagnostic procedure to verify a low charge.
If the problem is corrected, the ice machine is
low on charge. Find the refrigerant leak.
The ice machine must operate with the
nameplate charge. If the leak cannot be found,
proper refrigerant procedures must still be
followed Change the liquid line drier. Then,
evacuate and weigh in the proper charge.
2.
If the problem is not corrected by adding
charge, the expansion valve is faulty.
On dual expansion valve ice machines, change
only the TXV that is starving. If both TXV’s are
starving, they are probably good, and are being
affected by some other malfunction, such as low
charge.
COLUMN 3 - TXV FLOODING
A loose or improperly mounted expansion valve
bulb causes the expansion valve to flood. Check
bulb mounting, insulation, etc., before changing the
valve. On dual expansion valve machines, the
service technician should be able to tell which TXV
is flooding by analyzing ice formation patterns.
Change only the flooding expansion valve.
COLUMN 4 - COMPRESSOR
Replace the compressor and start components. To
receive warranty credit, the compressor ports must
be properly sealed by crimping and soldering them
closed. Old start components must be returned with
the faulty compressor.
Summary of Contents for Marine Q 1000
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