Mitsubishi Electric City Multi PQHY-P72 Service Handbook page 308

10) To adjust refrigerant amount, open the ball valves (BV1 and BV2) inside the heat source unit.
Note : When the power to the heat source/indoor unit must be turned off to repair the leak after closing the ball
valves specified in the item 5, turn the power off in approximately one hour after the heat source/indoor units
stop.
(i) When 30 minutes have passed after the item 4 above, the indoor unit lev turns from fully closed to slightly open
to prevent the refrigerant seal.
(ii) Therefore, if the power source is turned off within 30 minutes, the lev remains fully closed and the refrigerant
remains sealed.
When only the power for the indoor unit is turned off, the indoor unit LEV turns from faintly open to fully closed.
3. Leak spot: In the case of extension pipe for indoor unit (Heating season)
1) Run all the indoor units in heating test run mode.
(i) To run the indoor unit in test run mode, turn SW3-2 from ON to OFF when SW3-1 on the heat source unit MAIN
board is ON.
(ii) Change the setting of the remote controller for all the indoor units to the heating mode.
(iii) Check that all the indoor units are performing a heating operation.
2) Stop all the indoor units, and stop the compressor.
(i) To stop all the indoor units and the compressors, turn SW3-2 from ON to OFF when SW3-1 on the heat source
unit MAIN board is ON.
(ii) Check that all the indoor units are stopped.
3) Close the ball valves (BV1 and BV2).
4) Collect the refrigerant that remains inside the heat source unit. Do not discharge refrigerant into air into the atmo-
sphere when it is collected.
5) Repair the leak.
6) After repairing the leak, perform evacuation of the extension pipe for the indoor unit, and open the ball valves (BV1
and BV2) to adjust refrigerant.
4. Leak spot: In the case of heat source unit (Heating season)
1) Collect the refrigerant in the entire system (heat source unit, extended pipe and indoor unit).Do not discharge re-
frigerant into the atmosphere when it is collected.
2) Repair the leak.
3) After repairing the leak, replace the dryer with the new one, and perform evacuation of the entire system, and cal-
culate the standard amount of refrigerant to be added (for heat source unit, extended pipe and indoor unit), and
charge the refrigerant.
Refer to "8 [4] 3. "
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[ IX Troubleshooting ]