5-5
62-11848
5.4
REFRIGERANT LEAK CHECKING
A refrigerant leak check should always be performed after the system has been opened to replace or repair a com-
ponent. To check for leaks in the refrigeration system, perform the following procedure:
NOTE
Use only R-134a with dry nitrogen to pressurize the system. Any other gas or vapor will contaminate the
system which will require additional purging and evacuation of the high side (discharge) of the system.
a. The recommended procedure for finding leaks in a system is with an electronic leak detector. (Carrier P/N 07-
00295-00). Testing joints with soap suds is only satisfactory for locating large leaks.
b. Charge system with refrigerant to build up pressure between 30 to 50 psig (2.1 to 3.5 bar). Remove refriger-
ant cylinder and leak check all connections.
c. Remove refrigerant using a refrigerant recovery system (See
) and repair any leaks. Evacuate and
dehydrate the unit. (Refer to
5.5
EVACUATION AND DEHYDRATION
5.5.1
General
Moisture can seriously damage refrigerant systems. The presence of moisture in a refrigeration system can have
many undesirable effects. The most common are copper plating, acid sludge formation, “freezing-up” of metering
devices by free water, and formation of acids, resulting in metal corrosion.
5.5.2
Preparation
a. Evacuate and dehydrate only after pressure leak test. (Refer to
)
b. Essential tools to properly evacuate and dehydrate any system include a good vacuum pump (5 cfm =
8m
3
H volume displacement, P/N07-00176-01) and a good vacuum indicator such as a thermocouple vac-
uum gauge. (Carrier P/N 07-00414-00).
NOTE
Use of a compound gauge is not recommended because of its inherent inaccuracy.
c. Keep the ambient temperature above 60°F (15.6°C) to speed evaporation of moisture. If ambient tempera-
ture is lower than 60°F (15.6°C), ice might form before moisture removal is complete. Heat lamps or alter-
nate sources of heat may be used to raise system temperature.
d. Additional time may be saved during a complete system evacuation by replacing the filter-drier with a sec-
tion of copper tubing and the appropriate fittings. Installation of a new filter-drier may be performed during
the charging procedure.
5.5.3
Procedure For Evacuation And Dehydrating System
a. Remove refrigerant using a refrigerant recovery system.
b. The recommended method to evacuate and dehydrate the system is to connect three evacuation hoses to
the vacuum pump and refrigeration unit as shown in
. Do not use standard service hoses, as they
are not suited for evacuation purposes. Connect an evacuation manifold, with special evacuation hoses, to
the vacuum pump, electronic vacuum gauge, and to the refrigerant recovery system.
c. Make sure the vacuum gauge valve is closed and the vacuum pump valve is open.
d. Test the evacuation system for leaks by back-seating the king valve (or closing the field coupler connected to
the liquid line charging port), turning suction and discharge access valves counter clockwise to close, and draw-
ing a deep vacuum with the vacuum pump and gauge valves open. Shut off the pump and check to see if the
vacuum holds. Repair leaks if necessary.
e. Mid-seat the king valve or field couple connected to the liquid line charging port. Turn suction and discharge
access valves clockwise to open.
f. Open the vacuum pump and electronic vacuum gauge valves, if they are not already open. Start the vacuum
pump. Evacuate the unit until the electronic vacuum gauge indicates 2000 microns. Close the electronic vacuum
gauge and vacuum pump valves. Shut off the vacuum pump. Wait a few minutes to be sure the vacuum holds.
g. Break the vacuum with nitrogen. Raise system pressure to approximately 2 psig (0.14 Bar).
h. Repeat steps f. through h.
