4-- 5© 2012 Mobile Climate Control T-299 Rev. 08/2012
4.4 REFRIGERANT RECOVERY
To remove the entire refrigerant charge, do the
following:
a. Connect a manifold gauge set to the system as
showninFigure4-2.
b. Connect a reclaimer to the center m anifold gauge
set connection.
c. Recover refrigerant in accordance with reclaimer
manufacturers instructions.
4.5 REFRIGERANT LEAK CHECKING
A refrigerant leak check should always be performed
after the system has been opened to replace or repair
a component.
To check for leaks in the refrigeration system,
perform the following procedure:
WARNING
Never use air for leak testing. It has been
determined that pressurized, air-rich
mixtures of refrigerants and air can
undergo combustion when exposed to an
ignition source.
Note
Larger split systems may be equipped with
service valves and a liquid line solenoid.
Ensure th ese service valves are open and
power the liquid line service valve from an
external source.
a. If the system is without refrigerant, charge the
system with refrigerant vapor to build up pressure
to approximately 30 PSIG (R134a).
b. Add sufficient nitrogen to raise system pressure
to150/200 psig. (10.21/13.61 bar).
c. Check for leaks. The recomm en ded pro cedure for
finding leaks in a system is with a R-134a electronic
leak detector. Testing joints with soapsuds is
satisfactory and may be necessary under
conditions where when an electronic leak detector
will not function properly, such as with large leaks.
d. Remove test gas and replace filter-drier.
e. Evacuate and dehydrate the unit. (Refer to
paragraph 4.6.)
f. Charge the unit. (Refer to paragraph 4.8).
4.6 EVACUATION AND DEHYDRATION
4.6.1 General
The presence of moisture in a refrigeration system
can h ave many undesirable effects. The most
common are copper plating, acid sludge formation,
“freezing-up” of metering devices b y free water, and
formation of acids, resulting in metal corrosion. A
triple evacuation (Refer to paragraph 4.6.3) should
be performed after a major system repair
(compressor, evaporator, or condenser
replacement). A one time evacuatio n (Refer to
paragraph ) should take place after a minor system
repair, such as a filter-drier replacement.
4.6.2 Preparation
NOTE
Using a compound gauge for determination
of vacuum level is not recommended
because of its inherent inaccuracy.
a. Evacuate and dehydrate only after pressure leak
test. (Refer to paragraph 4.5 .)
b. Essential tools to properly evacuate and dehydrate
any system include a vacuum pump (6 cfm volume
displacement - (MCC P/N 07-00176-11) and an
electronic vacuum (micron) gauge (MCC P/N
07-00414-00).
c. Keep the ambient temperature above 60° F(15.6°
C) to speed evaporation o f moisture. If the
ambient temperature is lower than 60° F (15.6° C),
ice may form before moisture removal is
complete. Heat lamps or alternate sources of heat
maybeusedtoraisethesystemtemperature.
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