Lennox International Inc. 10ACB - Manual (Page 7)

3DJH 
5 -- Connect the high pressure hose of the manifold
gauge set to the service port of the suction valve.
(Normally, the high pressure hose is connected to
the liquid line port, however, connecting it to the
suction port better protects the manifold gauge set
from high pressure damage.)
6-- Adjust nitrogen pressure to 150 psig. Open the
valve on the high side of the manifold gauge set
which will pressurize line set and indoor unit.
7-- After a short period of time, open a refrigerant port
to make sure the refrigerant added is adequate to be
detected. (Amounts of refrigerant will vary with line
lengths.) Check all joints for leaks. Purge nitrogen
and HCFC-22 mixture. Correct any leaks and re-
check.
(9$&8$7,1*
Evacuating the system of non--condensables is critical
for proper operation of the unit. Non--condensables are
defined as any gas that will not condense under temper-
atures and pressures present during operation of an air
conditioning system. Non--condensables and water va-
por combine with refrigerant to produce substances
that corrode copper piping and compressor parts.
1-- Connect manifold gauge set to the service valve
ports as follows: low pressure gauge to suction
line service valve; high pressure gauge to liquid
line service valve.
2-- Connect the vacuum pump (with vacuum gauge)
to the center port of the manifold gauge set.
3-- Open both manifold valves and start vacuum
pump.
4-- Evacuate the line set and indoor unit to an absolute
pressure of 23mm of mercury or approximately 1
inch of mercury. During the early stages of evacua-
tion, it is desirable to close the manifold gauge
valve at least once to determine if there is a rapid
rise in absolute pressure. A rapid rise in pressure
indicates a relatively large leak. If this occurs, the
leak testing procedure must be repeated.
NOTE -- The term absolute pressure means the to-
tal actual pressure within a given volume or sys-
tem, above the absolute zero of pressure. Absolute
pressure in a vacuum is equal to atmospheric pres-
sure minus vacuum pressure.
5-- When the absolute pressure reaches 23mm of mer-
cury, close the manifold gauge valves, turn off the
vacuum pump and disconnect the manifold gauge
center port hose from vacuum pump. Attach the
manifold center port hose to a nitrogen cylinder
with pressure regulator set to 150 psig and purge
the hose. Open the manifold gauge valves to break
the vacuum in the line set and indoor unit. Close
the manifold gauge valves.
&$87,21
Danger of Equipment Damage.
Avoid deep vacuum operation. Do not use com-
pressors to evacuate a system.
Extremely low vacuums can cause internal arcing
and compressor failure.
Damage caused by deep vacuum operation will
void warranty.
6-- Shut off the nitrogen cylinder and remove the man-
ifold gauge hose from the cylinder. Open the man-
ifold gauge valves to release the nitrogen from the
line set and indoor unit.
7-- Reconnect the manifold gauge to the vacuum
pump, turn the pump on and continue to evacuate
the line set and indoor unit until the absolute pres-
sure does not rise above .5mm of mercury within a
20 minute period after shutting off the vacuum
pump and closing the manifold gauge valves.
8-- Depending on the equipment used to determine
the vacuum level, the following units are equiva-
lent to absolute pressure of .5mm of mercury or
500 microns.
9-- When the absolute pressure requirement above has
been met, disconnect the manifold hose from the
vacuum pump and connect it to an upright bottle of
HCFC-22 refrigerant. Open the manifold gauge
valves to break the vacuum in the line set and in-
door unit. Close manifold gauge valves and shut off
HCFC-22 bottle and remove manifold gauge set.