Mitsubishi Electric PUHY-HP120TNU-A, Service Handbook

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[8-11 Measures for Refrigerant Leakage ]
50
- chapter 8 HWE18240_GB
8 Troubleshooting Based on Observed Symptoms
8-11 Measures for Refrigerant Leakage
1. Leak spot: In the case of extension pipe for indoor unit or optional 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 stopped.
3) Stop all the indoor units; turn on SW4 (912) 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 (SW4 (912) 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 or optional 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 or optional unit.
9) To adjust refrigerant amount, open the service valves (BV1 and BV2) inside the outdoor unit and turn off SW4 (912).
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 SW4 (769) 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 (SW4 (when SW6-10 is
set to OFF)) on the outdoor unit control board.)
1) When Tc-TH6 is 10°C [18°F] or more : See the next item (3).
2) When Tc-TH6 is less than 10°C [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 SW4 (769) 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.
In the cooling cycle, the section between check valve CV1 and LEV2 will form a closed circuit.
Before recovering the refrigerant or evacuating the system, leave the unit in a stopped state for
at least 30 minutes and then open LEV2 and switch SW4 (988) from OFF to ON so that LEV1 and
LEV2 are in an open state. If this work is not performed, recovering the refrigerant or evacuating
the system may not be possible. (After completion of work, set SW4 (988) from ON to OFF.)
(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.
Tc self-diagnosis switch TH6 self-diagnosis switch
SW4
ON
1 2 3 4 5 6 7 8 9 10
SW4
ON
1 2 3 4 5 6 7 8 9 10
ON
1 2 3 4 5 6 7 8 9 10
The figure at left shows that the switches 1 through 5 are set to ON and 6 through 10 are set to OFF.