4-7
© 2015 Mobile Climate Control
T-367 Rev. 05/2015
4.4.3. Removing Entire System Charge
NOTES
It is recommen ded that the Filter/Drier b e
replaced after opening the refrigeration sys
tem for any repair.
WARNING
Use of an electro-magnetic valve as a
means of positive shutoff for service is
not recommended or good service prac
tice.
CAUTION
For Safety, the bus and A/C system
should be OFF, and lockout/tag out
procedures should be implemented.
To remove the entire refrigerant charge for system
component repair, do the following:
a. Connect a manifold gauge set to the system as
showninFigure4-5.
b. Connect a reclaimer to the center manifold gauge
set connection.
c. Energize the Liquid Line Solenoid Valve (LSV)
(Item 12 in Figure 4-5) using an external power
source (24 VDC).
d. Recover r efrigerant in accordance with reclaimer
manufacturers instructions.
e. After rep air is com pleted, a leak check should be
performed prior to system evacuation/dehydra
tion and charging. Refer to paragraph 4.5.
4.5 REFRIGERANT LEAK CHECK
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:
NOTE
It is emphasized that only the correct refrig
erant should b e u sed to pressurize th e sys
tem. Use of any other refrigerant will con
taminate the system.
a. Ensure the service valves are open.
b. Energize the Liquid Line Solenoid Valve (LSV)
(Item 12 in Figure 4-5) using an external power
source (24 VDC).
c. If system is without refrigerant, charge system
with refrigerant vapor to build up pressure to
approximately 30 PSIG (R-134a).
d. Add sufficient nitrogen to raise system pressure to
150 to 200 psig (10.21 to 13.61 bar).
e. Check for leaks. The recom m ended procedure for
finding leaks in a system is with an electronic leak
detector. Testing joints with soap suds is satisfac
tory and may be necessary under conditions when
an electronic leak detector will not function co r
rectly.
f. Remove test gas.
g. Evacuate and dehydrate the system. Refer to para
graph 4.6.
h. Charge the unit. Refer to Section 4.7.
4.6 EVACUATION AND DEHYDRATION
4.6.1 General
The presence of moisture in a refrigeratio n 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. A
triple evacuation (Refer to paragraph 4.6.4) should
be performed after a major system repair
(compressor, evaporator, or condenser
replacement). A one time evacuation (Refer to
paragraph 4.6.3) should take place after a minor
system repair (replacement of a solenoid valve or a
filter drier).
4.6.2 Preparation
NOTE
Using a compound gauge for determination
of vacuum level is not recommended be
cause of its inherent inaccuracy.
a. Evacuate and dehydrate only after pressure l eak
test. Refer to paragraph 4.5.
To Next Page
Loading...
