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6.3.3 Refrigerant Leak Checking
Never use air or gases containing oxygen
for leak testing or operating refrigerant
compressors. Pressurized mixtures of air
or gases containing oxygen can lead to ex-
plosion.
a. The recommended procedure for finding leaks in a
system is with a R-134a electronic leak detector.
Testing joints with soapsuds is satisfactory only for
locating large leaks.
b. If the system is without refrigerant, charge the system
with refrigerant 134a to build up pressure between 2.1
to 3.5 kg/cm
pressurization of the system, refrigerant should be
charged at the compressor suction valve, economiz-
er service valve and the liquid line service valve. Also,
the area between the suction modulating valve and
evaporator expansion valve may not be open to these
charging points. Pressure between these compo-
nents may be checked at the low side access valve or
by checking that the suction modulating valve is more
than 10% open at controller function code Cd01. The
suction modulating valve may be opened by use of
the controller function code Cd41 valve override con-
trol (refer to paragraph 6.17). Remove refrigerant cyl-
inder and leak-check all connections.
Only refrigerant 134a should be used to pres-
surize the system. Any other gas or vapor will
contaminate the system, which will require
additional purging and evacuation of the sys-
tem.
c. If required, remove refrigerant using a refrigerant
recovery system and repair any leaks. Check for
leaks.
d. Evacuate and dehydrate the unit. (Refer to paragraph
6.3.4.)
e. Charge unit per paragraph 6.3.5.
6.3.4 Evacuation and Dehydration
General
Moisture detrimental to refrigeration 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.
Preparation
a. Evacuate and dehydrate only after pressure leak test.
b. Essential tools to properly evacuate and dehydrate
any system include a vacuum pump (8 m
volume displacement) and an electronic vacuum
gauge. (The pump is available from Carrier Trans-
icold, part number 07-00176-11.)
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WARNING
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(30 to 50 psig). To ensure complete
NOTE
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c. If possible, keep the ambient temperature above
15.6C (60F) to speed evaporation of moisture. If the
ambient temperature is lower than 15.6C (60F), ice
might form before moisture removal is complete.
Heat lamps or alternate sources of heat may be used
to raise the system temperature.
d. Additional time may be saved during a complete sys-
tem pump down by replacing the filter drier with a sec-
tion of copper tubing and the appropriate fittings.
Installation of a new drier may be performed during
the charging procedure.
1
1. Liquid Service
Connection
2. Receiver or Water
Cooled Condenser
3. Compressor
4. Discharge Service
Connection
Figure 6- -4 Refrigeration System Service Connec-
Procedure - Complete System
Refer to Partial System procedure for informa-
tion pertaining to partial system evacuation and
dehydration.
a. Remove all refrigerant using a refrigerant recovery
system.
b. The recommended method to evacuate and dehy-
drate the system is to connect evacuation hoses at
3
/hr = 5 cfm
the compressor suction, compressor economizer
service connection and liquid line service valve (see
Figure 6--4). Be sure the service hoses are suited for
evacuation purposes.
6--3
3
2
S
D
10
8
9
7
5. Suction Service
Connection
6. Vacuum Pump
7. Electronic Vacuum
Gauge
8. Manifold Gauge Set
9. Refrigerant Cylinder
10. Reclaimer
tions
NOTE
4
5
6
T-334
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