Mitsubishi Electric PUHY-200YMF-B Service Handbook page 173

8 PREPARATION, REPAIRS AND REFRIGERANT REFILLING WHEN REPAIRING
LEAKS
[1] Location of leaks: Extension piping or indoor units (when cooling)
<PU(H)Y-(P)200·250YMF-B>
1 Connect a pressure gauge to the low-pressure servicing check joint CJ2.
2 Test run all indoor units in cooling mode.
1. With SW3-1 on the MAIN board of the outdoor unit set to ON and SW3-2 OFF → ON to test run all indoor
units.
2. Change the remote controller settings so that all indoor units run in cooling mode.
3. Check that all indoor units are running in cooling mode.
3 Perform a pump down operation.
1. Close the liquid ball valve (BV2) on the outdoor unit to begin the pump down.
4 When the pressure gauge on the low-pressure servicing check joint CJ2 reads 2 kg/cm
indoor units and the compressor.
1. With SW3-1 on the MAIN board of the outdoor unit set to ON and SW3-2 ON → OFF to stop all indoor units
and the compressor.
2. Check that all indoor units have been stopped.
5 Close the gas ball valve (BV1) on the outdoor unit.
6 Remove any refrigerant remaining in the extension piping or the indoor units.
Reclaim the refrigerant; do not discharge it into the air.
7 Repair the leak point.
8 After the leak point is repaired, extract all air from the extension piping and the indoor units to create a vacuum.
9 Open both ball valves (BV1 and BV2) on the outdoor unit, then adjust the refrigerant amount and verify that the
refrigerant is circulating properly.
<PURY-(P)200·250YMF-B> (Pump down operation)
1 Attach a pressure gage to the low-pressure servicing check joint (CJ2).
2 Stop all of the indoor units. When the compressor has stopped, shut off the liquid ball valve (BV2) for the outdoor
unit.
3 Stop all of the indoor units. When the compressor has stopped, turn the SW3-6 switch on the main board for the
outdoor unit to ON. (This will start the pump down operation causing all of the indoor units to enter the cooling
mode.)
4 While in the pump down operation (SW3-6 ON), the low pressure (LPS) will reach below at least 2 kg/cm
(0.20 MPa) or the indoor unit and the compressor will automatically shut down within 15 minutes of starting the
pump down operation. Shut down all of the indoor units and the compressor if the pressure gage for the low-
pressure servicing joint (CJ2) reads 1.5 kg/cm
minutes.
5 Shut off the gas ball valve (BV1) for the outdoor unit.
6 Remove any refrigerant remaining in the extension piping and the indoor units.
Be sure to recover the refrigerant without releasing it into the air.
7 Repair the location of the leak.
8 After repairing the leak, create a vacuum to remove any air from inside of the extension piping or the indoor
units.
9 Open the ball valves for the outdoor unit (BV1 and BV2), turn the SW3-6 switch to OFF, adjust refrigerant levels
and confirm proper circulation.
[2] Location of leaks: Outdoor unit (Cooling mode)
1 Test run all indoor units in cooling mode.
1. With SW3-1 on the MAIN board of the outdoor unit set to ON and SW3-2 OFF → ON to test run all indoor
units.
2. Change the remote controller settings so that all indoor units run in cooling mode.
3. Check that all indoor units are running in cooling mode.
2 G (0.15 MPa) or after running the pump down operation for 20
–171–
2
G (0.20MPa), stop all
2
G