MovinCool 24HFU Service Manual - Manual (Page 41)

MOVINCOOL 24HFU / 24HFU-1 SERVICE PAGE 41
REPAIR - INSPECTION AND REPAIR OF REFRIGERANT SYSTEM
5-1. Inspection
In most cases, the probable cause for insufficient cooling is a clogged system, leakage or an incorrect
amount of refrigerant. In such cases, inspect the system according to the following procedure.
5-2. Repair of Refrigerant System
In case there is a leak, obstruction, or trouble in the refrigerant system of the Spot Cooling System, replace
or repair the part in question. After replacing any component all connections must be brazed.
(1) BRAZED FITTING AND ITS
CLEARANCE
In general, the strength of brazing filler
metal is lower than that of the base
metal. So, the shape and clearance
of the brazed fitting are quite impor-
tant. As for the shape of the brazed
fitting, it is necessary to maximize its
adhesive area. The clearance of the
brazed fitting must be minimized to
facilitate brazing filler metal to flow
into it by capillary action.
■ Brazed Fitting and its Clearance
(2) CLEANING OF BRAZING FILLER
METAL AND PIPE
When the refrigerant system has been
opened up, exposure to heat may
have caused brazing filler metal to
stick to the inside and outside of the
pipe. Brazing filler metal may also be
compounded with oxygen in the air to
form oxide film. Fats and oils may
stick to the pipe from handling. All
these factors will reduce effectiveness
of brazing. It is necessary to eliminate
excess brazing filler metal using sand
paper and by cleaning thoroughly with
a solvent such as Trichlene.
5-2-1. Proper Brazing Techniques
It is desirable to use a slightly reducing flame. Oxyacetylene is commonly used since it is easy to
judge and adjust the condition of the flame. Unlike gas welding, a secondary flame is used for
brazing. It is necessary to preheat the base metal properly depending on the shape, size or thermal
conductivity of the brazed fitting.
The most important point in flame brazing is to bring the whole brazed fitting to a proper brazing
temperature. Care should be taken to not cause overflow of brazing filler metal, oxidization of brazing
filler metal, or deterioration due to the overheating of flux.
5-1-1. Inspection of Clogged System
Check the component parts of the refrigerant system, including piping, that could be clogged with
refrigerant. If clogged with refrigerant, only the clogged part is frosted partially. In such a case,
change the part in question.
5-1-2. Inspection of Refrigerant Leak
Carefully check all connections, and each component for leaks whenever the refrigerant system is
installed or repaired. Use an electronic gas leak tester to inspect the system.
5-1-3. Insufficient Refrigerant
In case the unit is judged to be deficient in cooling capacity, be sure to perform the inspections in
5-1-1. and 5-1-2. to confirm the cause of trouble. After that, charge the system with refrigerant.