Refrigeration System Repair; Brazing - Denso MOVINCOOL Climate pro k18 Service Manual

REFRIGERATION SYSTEM REPAIR

Brazing

If a problem with refrigerant system is found, replace or repair the relevant part. After replacing any
part, all connections must be brazed.
To avoid burns, lack of oxygen or unit malfunction:
• Brazing must be performed by a qualified technician only.
• When brazing, always wear eye protection and gloves.
• Work in a well-ventilated area only.
1. Proper brazing techniques
It is desirable to use a slightly reduced 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 not to cause
overflow of brazing filler metal, oxidization of brazing filler metal, or deterioration due to the
overheating of flux.
2. Shape and clearance of brazed fitting
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 the flow of the brazing metal filler by
capillary action.
3. Cleaning brazing filler metal and pipe
The surface of the metal combines with oxygen in the air and becomes covered with a very
thin oxide film. Fats and oils often adhere to pipes due to handling. The metal and pipes must be
cleaned before brazing. Fats and oils should be removed with a solvent such as trichlene. Rust
and oxide should be removed with sand paper.
• Do not use cleaners that contain chlorine. Chlorine cleaners may damage pipes.
WARNING
a
Clearance From Pipe Fitting and Tubing
CAUTION
44
Clearance
0.001~0.003 inch
(0.025~0.075 mm)