Leak Check And System Evacuation - Trane MCC Series Installation Manual

Leak Check
After the connection operation of
refrigerant lines to both the outdoor
and indoor unit is completed, the field
brazed connections must be checked
for leaks. Pressurize the system
through the service valve with dry
nitrogen to 250 psi. Use soap
bubbles or other leak-checking
methods to ensure that all field joints
are leak free. If not, release pressure,
repair and repeat leak test.
System Evacuation
1. After completion of leak check,
evacuate the system.
2. Attach appropriate hoses from
manifold gauge to gas and liquid
line pressure taps.
Note: Unnecessary switching of
hoses can be avoided and
complete evacuation of all lines
leading to sealed system can be
accomplished with manifold
center hose and connecting
branch hose to a cylinder of
R-22 and vacuum pump.
3. Attach center hose of manifold
gauges to vacuum pump.
4. Evacuate the system to hold a
350 micron vacuum.
5. Close off valve to vacuum pump
and observe the micron gauge.
If gauge pressure rised above
500 microns in one (1) minute,
then evacuation is incomplete or
the system has a leak.
6. If vacuum gauge does not rise
above 500 microns in one (1)
minute, the evacuation should
be complete.
7. With vacuum pump and micron
gauge blanked off, open valve on
R-22 cylinder and allow refrigerant
pressure to build up to about 40
psig.
MCC-SVN01A-EN

Leak Check and System Evacuation

8. Close valve on the R-22 supply
cylinder. Close valves on manifold
gauge set and remove refrigerant
charging hoses from liquid and
gas gauge ports.
9. Leak test the entire system. Using
proper procedures and caution,
repair any leaks found and repeat
the leak test.
Refrigerant Charging Procedure
Charge refrigerant through the gauge
port on the liquid line until pressure at
gauge is up to 120-150 psi. Once the
charge enters the system, backseat
(open) the liquid line service valve and
disconnect the charging line and
replace the cap on the gauge port.
Gaseous Charging
This procedure is accomplished
with the unit operating. Electrical
connections must be complete.
Do not proceed until the system is
ready to operate.
Procedure
1. Connect R-22 drum with gauge
manifold to the Schrader valves
(pressure taps) on the compressor
discharge and suction lines.
2. Turn on power to the unit. Allow
the system to run for five to ten
minutes to stabilize operating
conditions.
3. Once proper airflow is established,
observe the suction and head
pressure gauges on the gauge
manifold. Pressure reading should
fall approximately at the normal
points. Add or remove refrigerant
(gas only) as required to obtain
correct head and suction pressures.
Check suction line superheat and
condenser sub-cooling to ensure
the unit is operating properly.
4. Disconnect all power to the unit.
5. Remove the charging system from
the unit and close the opening in
the bottom of the control box with
the pivotal cover before attempting
to replace access panel.
Liquid pressure
Electrical connection
Liquid line
Suction
line
Service hose
Figure 16
Suction pressure
Vacuum pump
R-22
7