Manitowoc-ice MARINE MODEL S1800 Manuel d'utilisateur télécharger pdf (Page 83)

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Section 7 Refrigeration System

Part Number 80-1634-3 7-17

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 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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Manitowoc-ice MARINE MODEL S1800 Manuel d'utilisateur Page 83

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