Section 7 | Refrigeration System |
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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
NOTE: Before starting, see “Before Beginning Service” for a few questions to ask when talking to the ice machine owner.
Procedure
Step 1 Record the ice machine model number. Step 2 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.
NOTE: Discharge Line Temperature will vary by model. Refer to the model number to verify the correct temperature to analyze.
Step 3 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 4 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 - HARVEST VALVE LEAKING
A leaking harvest valve must be replaced.
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 they 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.
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