Armstrong Air 4SCU 16LS Series, Installation And Maintenance Instructions Manual

Page: 12 / 32

506859-01 Issue 1236 Page 12 of 32
Using an Electronic Leak Detector
1. Connect the high pressure hose of the manifold gauge
set to the suction valve service port. (Normally the
high pressure hose is connected to the liquid line port;
however, connecting it to the suction ports helps to
protect the manifold gauge set from damage caused
by high pressure.)
2. With both manifold valves closed, connect the cylinder
of R410A refrigerant. Open the valve on the R410A
cylinder (vapor only).
3. Open the high pressure side of the manifold to allow
R410A into the line set and indoor unit. Weigh in a trace
amount of R410A. (A trace amount is a maximum of 2
oz. of refrigerant or 3 lbs. pressure.) Close the valve on
the R410A cylinder and the valve on the high pressure
side of the manifold gauge set. Disconnect the R410A
cylinder.
4. Connect a cylinder of nitrogen with a pressure regulating
valve to the center port of the manifold gauge set. When
using high pressure gas such as nitrogen for this
purpose, be sure to use a regulator that can control
the pressure down to 1 or 2 psig.
5. Adjust nitrogen pressure to 150 psig. Open the valve
on the high side of the manifold gauge set to pressurize
the line set and the indoor coil.
6. After a short period of time, open a refrigerant port to
make sure that an adequate amount of refrigerant has
been added for detection (refrigerant requirements will
vary with lenths). Check all joints for leaks. Purge
nitrogen and R410A mixture. Correct any leaks and
rechecks.
Evacuation
Evacuating the system of noncondensables is critical for
proper operation of the unit. Noncondensables are defined
as any gas that will not condense under temperatures and
pressures present during operation of an air conditioning
system. Noncondensables and water vapor combine with
refrigerant to produce substances that corrode copper piping
and compressor parts.
Use a thermocouple or thermistor electronic vacuum gauge
that is calibrated in microns. Use an instrument that reads
down to 50 microns.
1. Connect the 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 micron gauge.
Do not use a compressor to evacuate a system. Avoid
deep vacuum operation. Extremely low vacuums can
cause internal arcing and compressor failure. Danger of
equipment damage. Damage caused by deep vacuum
operation will void warranty.
WARNING
Refrigerant can be harmful if inhaled. Refrigerant must
always be used and recovered responsibly. Incorrect
or irresponsible use of refrigerant can result in personal
injury or death.
WARNING
Never use oxygen to pressurize refrigeration or air
conditioning systems. Oxygen will explode on contact
with oil and could cause personal injury or death.
WARNING
Figure 14