Mitsubishi Electric PUHY-(E)P300, Service Handbook

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[
IX
Troubleshooting ]
- 241 -
HWE07010 GB
[5] Refrigerant Leak
1. Leak spot: In the case of extension pipe for indoor unit (Cooling season)
1) Mount a pressure gauge on the service check joint (CJ2) on the low-pressure side.
2) Stop all the indoor units, and close the liquid service valve (BV2) inside the outdoor unit while the compressor is being stopped.
3) Stop all the indoor units; turn on SW2-4 on the outdoor unit control board while the compressor is being stopped.(Pump down
mode will start, and all the indoor units will run in cooling test run mode.)
4) In the pump down mode (SW2-4 is ON), all the indoor units will automatically stop when the low pressure (63LS) reaches
0.383MPa [55psi] or less or 15 minutes have passed after the pump mode started. Stop all the indoor units and compressors
when the pressure indicated by the pressure gauge, which is on the check joint (CJ2) for low-pressure service, reaches
0.383MPa [55psi] or 20 minutes pass after the pump down operation is started.
5) Close the gas service valve (BV1) inside the outdoor unit.
6) Collect the refrigerant that remains in the extended pipe for the indoor unit. Do not discharge refrigerant into the atmosphere
when it is collected.
7) Repair the leak.
8) After repairing the leak, vacuum the extension pipe and the indoor unit.
9) To adjust refrigerant amount, open the service valves (BV1 and BV2) inside the outdoor unit and turn off SW2-4.
2. Leak spot: In the case of outdoor unit (Cooling season)
(1) Run all the indoor units in the cooling test run mode.
1) To run the indoor unit in test run mode, turn SW3-2 from ON to OFF when SW3-1 on the outdoor control board is ON.
2) Change the setting of the remote controller for all the indoor units to the cooling mode.
3) Check that all the indoor units are performing a cooling operation.
(2) Check the values of Tc and TH6.
(To display the values on the LED screen, use the self-diagnosis switch (SW1) on the outdoor unit control board.)
1) When Tc-TH6 is 10K [18°F] or more : See the next item (3).
2) When Tc-TH6 is less than 10K [18°F] : After the compressor stops, collect the refrigerant inside the system, repair the leak,
perform evacuation, and recharge new refrigerant. (Leak spot: 4. In the case of outdoor unit, handle in the same way as heat-
ing season.)
(3) Stop all the indoor units, and stop the compressor.
1) To stop all the indoor units and the compressors, turn SW3-2 from ON to OFF when SW3-1 on the outdoor control board is ON.
2) Check that all the indoor units are being stopped.
(4) Close the service valves (BV1 and BV2).
(5) To prevent the liquid seal, extract small amount of refrigerant from the check joint of the liquid service valve (BV2),
as the liquid seal may cause a malfunction of the unit.
(6) Collect the refrigerant that remains inside the outdoor unit.Do not discharge refrigerant into air into the atmosphere
when it is collected.
(7) Repair the leak.
(8) After repairing the leak, replace the dryer with the new one, and perform evacuation inside the outdoor unit.
(9) To adjust refrigerant amount, open the service valves (BV1 and BV2) inside the outdoor unit.
When the power to the outdoor/indoor unit must be turned off to repair the leak after closing the service valves specified in
the item 4, turn the power off in approximately one hour after the outdoor/indoor units stop.
1) 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.
LEV2a and LEV2b open when the outdoor unit remains stopped for 15 minutes to allow for the collection of refrigerant in the
outdoor unit heat exchanger and to enable the evacuation of the outdoor unit heat exchanger.
If the power is turned of in less than 5 minutes, LEV2a and LEV2b may close, trapping high-pressure refrigerant in the outdoor
unit heat exchanger and creating a highly dangerous situation.
2) 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.
Tc self-diagnosis switch TH3 self-diagnosis switch
ON
1 2 3 4 5 6 7 8 9 10
SW1
1 2 3 4 5 6 7 8 9 10
ON
SW1