Daikin DZ9VC - Refrigerant System Service; Line Connections and Brazing; Leak Testing and Evacuation

7
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IMPORTANT: To avoid overheating the service valve, TXV,
sensor, or lter drier while brazing, wrap the component with
a wet rag, or use a thermal heat trap compound. Be sure to
follow the manufacturer’s instruction when using the heat
trap compound. Note: Remove Schrader valves from ser-
vice valves before brazing tubes to the valves. After brazing
temperature is reached, use a brazing alloy of 2% minimum
silver content. Do not use ux
Torch heat required to braze tubes of various sizes is propor-
tional to the size of the tube. Tubes of smaller size require less
heat to bring the tube to brazing temperature before adding
brazing alloy. Applying too much heat to any tube can melt
the tube. Service personnel must use the appropriate heat
level for the size of the tube being brazed.
NOTE: The use of a heat shield when brazing is recommend-
ed to avoid burning the serial plate or the nish on the unit.
1. The ends of the refrigerant lines must be cut square,
deburred, cleaned, and be round and free from nicks
or dents. Any other condition increases the chance of
a refrigerant leak.
2. Purge with nitrogen at 2 to 3 psig during brazing
to prevent the formation of copper-oxide inside
the refrigerant lines. The FVC oils used in R-410A
applications will clean any copper-oxide present
from the inside of the refrigerant lines and spread it
throughout the system. This may cause a blockage or
failure of the metering device.
3. After brazing, quench the joints with water or a wet
cloth to prevent overheating of the service valve.
4. A bi-ow lter drier is shipped with the unit as a separate
component and must be brazed on by the installer on-
site. Ensure the bi-ow lter drier paint nish is intact
after brazing. If the paint of the steel lter drier has
been burned or chipped, repaint or treat with a rust
preventative.
The recommended location of the lter drier is before
the expansion device at the indoor unit.
NOTE: Be careful not to kink or dent refrigerant lines. Kinked
or dented lines will cause poor performance or compressor
damage.




Using dry nitrogen, pressurize the system to 450 PSIG.
Allow the pressure to stabilize and hold for 15 minutes
(minimum). If the pressure does not drop below 450 PSIG
the system is considered leak free. Proceed to system
evacuation using the Deep Vacuum Method. If after 15
minutes the pressure drops below 450 PSIG follow the
procedure outlined below to identify system leaks. Repeat
the Standing Pressure Test.

WARNING
TO AVOID THE RISK OF FIRE OR EXPLOSION, NEVER USE
OXYGEN, HIGH PRESSURE AIR OR FLAMMABLE GASES FOR
LEAK TESTING OF A REFRIGERATION SYSTEM.
WARNING
TO AVOID POSSIBLE EXPLOSION, THE LINE FROM THE
NITROGEN CYLINDER MUST INCLUDE A PRESSURE
REGULATOR AND A PRESSURE RELIEF VALVE. THE
PRESSURE RELIEF VALVE MUST BE SET TO OPEN AT NO

Leak test the system using dry nitrogen and soapy water
to identify leaks. If you prefer to use an electronic leak
detector, charge the system to 10 PSIG with the appropriate
system refrigerant (see Serial Data Plate for refrigerant
identication). Do not use an alternative refrigerant. Using
dry nitrogen nish charging the system to 450 PSIG. Apply
the leak detector to all suspect areas. When leaks are
discovered, repair the leaks, and repeat the pressure test. If
leaks have been eliminated proceed to system evacuation.

Condensing unit liquid and suction valves are closed to
contain the charge within the unit. The unit is shipped with
the valve stems closed and caps installed. Do not open
valves until the system is evacuated.
WARNING
REFRIGERANT UNDER PRESSURE!
FAILURE TO FOLLOW PROPER PROCEDURES MAY CAUSE
PROPERTY DAMAGE, PERSONAL INJURY OR DEATH.
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CAUTION
PROLONGED OPERATION AT SUCTION PRESSURES LESS

OVERHEATING OF THE SCROLLS AND PERMANENT DAMAGE
TO THE SCROLL TIPS, DRIVE BEARINGS AND INTERNAL
SEAL.