Service manual

Refrigeration System Section 7
7-20
Part No. 80-1206-3
REFRIGERATION COMPONENT
DIAGNOSTIC CHART
General
All electrical and water related problems must be
corrected before these chats will work properly. These
tables must be used with charts, checklists and other
references to eliminate refrigeration components not
listed and external items and problems that will cause
good refrigeration components to appear defective.
The tables list four different defects that may affect the
ice machine’s operation.
Procedure
Step 1 Complete each item individually in the
“Operation Analysis” column.
Enter check marks in the 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.
Perform the procedures and check all information listed.
Each item in this column has supporting reference
material.
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 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 - COOL VAPOR VALVE LEAKING
A leaking cool vapor valve must be replaced.
COLUMN 2 - LOW CHARGE/TXV STARVING
Normally, a starving expansion valve only affects the
freeze cycle suction, discharge pressure and ice fill
pattern. A low refrigerant will first affect the harvest cycle
pressures. As more refrigerant is lost the freeze cycle
pressures and fill pattern are affected. Verify the ice
machine is not low on charge before replacing an
expansion valve. Weigh the refrigerant when it is
recovered and verify the amount recovered matches the
ice machine model/serial plate amount.
COLUMN 3 - REFRIGERANT OVERCHARGE OR 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.
Verify refrigerant amount is correct by weighing
recovered refrigerant before replacing a TXV. 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
soldered closed to prevent oil leakage in transit. Old
start components must be returned with the faulty
compressor.