550.38-N1Y
Unitary Products Group
7
®
3.
Carefully remove the brazed plugs from the evaporator
liquid and vapor connections after relieving the pressure
in the evaporator.
4.
Braze the liquid line to the evaporator liquid connection.
The nitrogen should now be flowing through the evaporator
coil.
5.
Slide the grommet away from the vapor connection at
the coil. Braze the vapor line to the evaporator vapor
connection. After the connection has cooled, slide the
grommet back into original position.
6.
Protect the vapor valve of the outdoor unit with a wet rag
and braze the vapor line connection. The nitrogen flow
should be exiting the system from the vapor service port
connection. After this connection has cooled, remove the
nitrogen source from the liquid fitting service port.
7.
Replace the schrader cores in the liquid and vapor
valves.
8.
Evacuate the vapor line, evaporator and the liquid line, to
500 microns or less.
9.
Leak test all refrigerant piping connections including the
service port flare caps to be sure they are leak tight. DO
NOT OVERTIGHTEN (between 40 and 60 inch - lbs.
maximum).
NOTE: Do not use the system refrigerant in the outdoor unit to
purge or leak test.
10. Replace caps on service ports. Do not remove the flare
caps from the service ports except when necessary for
servicing the system.
11. Release the refrigerant charge into the system. Open
both the liquid and vapor valves by removing the plunger
cap and with an allen wrench back out counter-clockwise
until valve stem just touches retaining ring. Release the
refrigerant charge into the system. See “PRECAUTIONS
DURING BRAZING ANGLE VALVE” on page 6.
Replace plunger cap finger tight, then tighten an additional
1/12 turn (1/2 hex flat). Cap must be replaced to prevent
leaks.
If a leak is suspected, leak test to locate the leak. To verify
the leak, close the valve to the vacuum pump suction to iso-
late the pump and hold the system under vacuum. If the
micron gauge indicates a steady and continuous rise after a
few minutes, it's an indication of a leak. If the gauge shows a
rise, then levels off after a few minutes and remains fairly
constant, its an indication that the system is leak free, but still
contains moisture and may require further evacuation if the
reading is above 1000 microns.
12. If the refrigerant tubing, indoor evaporator coil or outdoor
condensing unit has developed a leak during shipment,
or was, for any other reason, opened to the atmosphere
for more than four (4) minutes, it is necessary to evacu-
FIGURE 6 : HEAT PROTECTION
If visual verification of the valve stem reaching the
retaining ring is impossible, stop backing out the.valve
stem when the slightest increase in resistance is felt.
Because of the small size and therefore the reduced
resistance, back out the liquid valve 5 turns maximum
to prevent going past the retaining ring.
The evaporator is pressurized.
Do not connect manifold gauges unless trouble is
suspected. Approximately 3/4 ounce of refrigerant
will be lost each time a standard manifold gauge
is connected.
