mum clockwise position. The discharge service valve is
shipped in the open position, and it will only be used if the com-
pressor requires service.
The liquid and suction line service valves have a 1/4" male flare
access port for evacuating, charging and pressure checking
the system.
NOTE: Never remove a cap from an access port unless the
valve is fully back-seated with its valve stem in the
maximum counter-clockwise position because the re-
frigerant charge will be lost. ALWAYS USE A REFRIG-
ERATION VALVE WRENCH TO OPEN AND CLOSE
THESE SERVICE VALVES.
EXTENDING THE SERVICE PORTS
(Refer to Fig. 6:)
1. Loosen the screws securing the service ports in shipping
position. (See FIG 5).
2. Push the service ports through the corner post.
3. Tighten the screws to secure the service ports for installa-
tion.
INSTALLATION
Since the condensing units are shipped with a holding charge of
refrigerant-22, they can be checked for a refrigerant leak by de-
pressing the stem on either of the service ports that extend
through the cabinet. As soon as some internal pressure is re-
lieved release the stem. DO NOT release the entire holding
charge.
If the unit has already lost its holding charge, it should be leak
tested and the necessary repairs should be made. If the unit
has maintained its holding charge, you can assume that it has
no leaks and proceed with the installation.
CAUTION: Dry nitrogen should always be supplied through a
connection while it is being brazed or unbrazed be-
cause the temperature required to make or break a
brazed joint is sufficiently high to cause oxidation
of the copper unless an inert atmosphere is pro-
vided. The flow of nitrogen should be continued un-
til the joint has cooled.
When making a braze connection, wrap a wet rag
around all tubing inside the unit to help prevent
damage to other components.
WARNING: The dry nitrogen should always be supplied
through a pressure regulating valve.
Before installing the liquid line between the condensing unit
and the evaporator coil, prepare as follows:
1. Burnish the external surfaces of the liquid connection on
the condensing unit and the end of the field-supplied piping
for the liquid line.
NOTE: Clean surfaces are essential for a well-brazed con-
nection.
2. Carefully clean the internal surfaces of the above. Any par-
ticles left on these surfaces may lead to a future system
malfunction.
NOTE: Use only copper tubing that has been especially
cleaned and dehydrated for refrigerant use. If the
tubing has been open for an extended period of
time, it should be cleaned before being used.
The liquid line connections can now be brazed while maintaining
a minimum flow of dry nitrogen through the piping as follows:
1. Remove the cap from the 1/4" access port on the liquid line
service valve.
2. Connect a supply of dry nitrogen to this access port.
NOTE: The filter-drier should be installed in the liquid line as
close to the evaporator coil as possible.
Do not allow the filter-drier to be exposed to the atmos-
phere for an extended period of time. Once it absorbs
moisture from the atmosphere, it loses its effective-
ness.
The matched air handlers are shipped with a small R-22
charge and they should be checked for leaks before installa-
tion.
1. Drill a small hole through the sealing cap or disc in both the
liquid and suction connection. If there is a pressure re-
lease, the evaporator has no leaks and you can proceed
with installation. If the charge has been lost, the coils
should be leak tested and the necessary repairs made.
2. Move the dry nitrogen supply from the access port on the
liquid line service valve of the condensing unit to the hole
through the suction disc on the evaporator coil.
3. Unbraze the coil's liquid line disc while maintaining a flow of
dry nitrogen across the connection and through the hole in
the liquid line disc.
NOTE: If the liquid line has a solenoid valve, the valve
should be opened manually to permit the nitrogen
to flow freely.
4. After the disc has been removed, burnish the external sur-
faces and clean the internal surfaces as outlined above.
5. Move the dry nitrogen supply back to the access port on the
liquid line service valve.
6. Braze the liquid line to the liquid connection on the evapo-
rator coil while maintaining a minimum flow of dry nitrogen
through the liquid line, the evaporator coil and the hole in
the suction disc.
7. Unbraze the disc on the suction connection of the evapora-
tor coil while maintaining the flow of dry nitrogen.
8. After the disc has been removed, burnish the external sur-
faces and clean the internal surfaces as outlined above.
The suction piping can now be brazed to the suction connec-
tion on the evaporator coil while maintaining a minimum flow of
dry nitrogen.
Before brazing the suction line to the condensing unit;
1. Move the dry nitrogen supply to the access port on the suc-
tion service valve of the condensing unit.
2. Burnish the external surfaces and clean the internal surfaces
of both the suction connection and the suction piping.
The suction line can now be brazed to the suction connection
on the condensing unit while maintaining the flow of dry nitro-
gen.
After the liquid and suction lines have been installed, the sys-
tem should be evacuated and charged.
EVACUATION AND CHARGING
With the liquid and suction line service valves closed, connect
a vacuum pump through a charging manifold to the access
ports on both the liquid and suction line service valves.
NOTE: The vacuum pump connection should be short and
no smaller than 3/8" O.D.
The refrigerant lines and the evaporator coil can now be evacu-
ated to 500 Microns without disturbing the charge in the con-
denser coil or the compressor.
After proper evacuation and dehydration, charge refrigerant
through the access port on the liquid line service valve allowing
the vacuum to draw in as much refrigerant as possible.
CAUTION: Do not charge liquid refrigerant through the com-
pressor suction connection.
Unitary Products Group
9
035-17393-000 Rev. A (0501)
