AUX air conditioner service manual
198
Pollution degree of refrigerating system can be classified as: slightly polluted and seriously polluted.
When system is slightly polluted, condensed oil in it has not been polluted completely, and if
refrigerant and lubricant is released from line of compressor, it is transparent and will become light
yellow(normally they should be in white) if tested with litmus paper. If system has been seriously
polluted, when line of compressor is opened, tar odor can be smelt immediately, and condensed oil
from line is black, and if litmus paper is put into the oil, it will become mahogany in 5 minutes.
Refrigerant in totally enclosed compressor for small air conditioner shall be R22 which can be cleaned
with R113 (C
2
F
3
CL
3—
trichloroethane
)
according to following procedure:
⑴ Release refrigerant in refrigerating system, check color and odor to determine the pollution degree
of refrigerating system;
⑵ Remove compressor, release a little refrigerant from technical tube to check its color and odor, and
inspect whether there’s any foreign substance.
⑶ Fill liquid tank with R113, and then start pump to clean the system. For the slightly polluted
system, pump only need to run around 1 hour, but serious polluted system should be washed for
3~4 hours. If washing need to last for a long time, cleaning agent is dirty and filter has been
blocked and smudged, and so shall be replaced.
⑷ Cleaning agent shall be recovered after the system has been cleaned, and can be reused after being
treated. Cleaning agent in liquid tank shall be recovered from liquid tube.
⑸ When cleaning has finished, refrigerating system shall be purged with nitrogen and dried.
In the foregoing sketch, parts in broken line pane shall be disconnected from line as the system is
being dried. Blinds shall be installed on the flange disk of liquid squeeze line and liquid suction line;
to dry the system quickly, blow heat wind outside the refrigerating line when system is being
evacuated by vacuum pump. Install the refrigerating system again, and replace compressor and filter
with new ones.
Following aspects shall be noticed during cleaning
⑴ To avoid cleaning agent leaking out, pressure resistant hose shall be used and connection
joints shall be packed tightly.
⑵ Replace capillary or expansion with by pass pipe or pressure resistant pipe and connect
evaporator and condenser directly;
⑶ Water in refrigerating system shall be drained completely;
⑷ If compressor has been burned, acid in system shall be purged with nitrogen.
⑸ Compressor, expansion valve (capillary) and filter shall be cleaned with gasoline first and then be
dried with nitrogen.
2. Blowing of refrigerating system
After refrigerating machine has been removed, inevitably, there’re some slag, rust, scale and water in
the system which will abrade running parts, for example, score and rough the cylinder or pistol surface,
or impress concave on the contact surface of some parts, for example, blades of compressor becomes
rough, and valve spool has been damaged. Sometimes dirt may block system on the expansion valve,
capillary and filter (dirt block). Dirt and water also reflects with refrigerant and condensate and create
corrosive substance. Currently, cleaning equipment is rarely used to clean refrigerating system. High
pressure nitrogen is often used to blow the polluted system.
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