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10
OUTDOOR UNIT REFRIGERANT
RECOVERY METHOD
10-1. Refrigerant Recovery from Failed Outdoor Unit
(Pump-Down)
This product supports refrigerant pump-down, a function which allows refrigerant to be recovered from an outdoor
unit in need of repair using a normal outdoor unit in a system featuring multiple outdoor units.
10-1-1. Note for refrigerant recovery operation
When performing pump-down operation, take note of the following matters:
Note 1: The pump-down refrigerant recovery rate changes with outside temperature and other factors.
After pump-down is completed, recover any residual gas using a refrigerant recovery device, etc., and be
sure to measure the amount of recovered refrigerant. (The refrigerant recovery rate can be improved by
heating the accumulator of the outdoor unit to be repaired during pump-down operation.)
Note 2: If pump-down has been performed, the system cannot be operated until the faulty outdoor unit is
repaired.
(Continued operation would be impossible due to a refrigerant overcharge.)
Note 3: If outdoor PMVs 1 and 2 both happen to be faulty (unable to open) or PMV 4 fails while fully closed, the
refrigerant in the heat exchangers (or sub-heat exchangers) cannot be recovered. In that case, recover
any residual gas in the heat exchangers (or sub-heat exchangers) using a tube piercing valve or some
other tool. After a pump-down operation, do not perform any welding until the residual gas in the heat
exchangers is recovered.
10-1-2. Refrigerant recovery procedure A (Case of no outdoor unit
backup operation setting)
<Work procedure>
Turn on the power supply to the system at the source, but leave the system switched off.
If the fault involves poor insulation of a compressor motor, remove the motor leads before the power is turned on.
[Setup of failed outdoor unit]
(1) Connect the check joint of liquid pipe and the low pressure-side check joint using a charge hose, and purge the
hose of air (to recover refrigerant from the liquid tank and heat exchangers).
(2) Fully close the liquid pipe service valve of the failed outdoor unit.
(Leave the service valves of the gas and balance pipes fully open.)
(3) If the oil is likely to has degraded due to a compressor fault, disconnect the SV3A valve connector of the failed
outdoor unit (to prevent the degraded oil from flowing into other outdoor units).
(4) Set SW01/02/03 on the interface P.C. board of the failed outdoor unit to 2/11/1. After [rd] [... ... ...] is displayed
on the 7-segment display, press SW04 and hold for 5 seconds or more.
– 242 –
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