3-4. Practical Work For Heavy Repair
TROUBLE DIAGNOSIS
- 87 -
Items Precautions
1. Removal of residual
refrigerant.
1) Continue to recover the refrigerant for more than 5 minutes after turning the refrigerator off.
2) Install a piercing type valve on the high pressure line (drier side). Then use the appropriate
recovery equipment to recover the refrigerant from the system. When the refrigerant has
been recovered, install a piercing type valve on the low pressure side. IT IS IMPORTANT
TO OPEN THE SYSTEM IN THIS ORDER TO KEEP THE OIL FROM BEING FORCED OUT.
The use of piercing type valves will allow future servicing and eliminates the possibility of a
defective pinch off.
2. Nitrogen blowing
welding.
When replacing a drier:
Weld and parts by blowing nitrogen (0.1~0.2kg/cm
2
) to high pressure side after
assembling a drier.
When replacing a compressor:
Weld and parts by blowing nitrogen to the low pressure side.
Note) For other parts, nitrogen blowing is not necessary because it does not produce oxidized
scales inside pipe because of its short welding time.
3. Replacement of drier.
Inserting a capillary tube
Measure distance with a ruler and put a mark (12
+3/-0
) on the capillary tube. Insert tube to the
mark and weld it.
KEY POINT
Observe the sequence for
removal of refrigerant.
(If not, compressor oil may
leak.)
KEY POINT
Welding without nitrogen
blowing produces oxidized
scales inside a pipe, which
affect performance and
reliability of a product.
KEY POINT
Be sure to check the
inserted length of capillary
tube when it is inserted.
(If inserted too far, the
capillary tube will be
blocked by the filter.)
Compressor
Low pressure side
Condenser
High pressure side
Drier
Evaporator
Release
Refrigent
Intake
Suction
Hot Line
1 2 1
2
Evaporator
Drier
High pressure side
Condenser
Refrigent
Intake
Hot Line
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