Carrier MMY-MAP0724FT9UL Service Manual page 211

(6) Approx. 10 minutes after the system starts up, fully close the gas pipe service valve of the failed outdoor
unit.
(7) Push SW04 of the failed outdoor unit to have pressure data psi (MPa) displayed.
(The display switches each time SW04 is pushed.)
Display Example
[rd] [...11]
Initial display
[Selection of outdoor unit for pressure adjustment]
(8) The outdoor units operating in the pump-down mode, is selevted to the outdoor unit for pressure
adjustment.
Identifying Unit No.
The unit No. is the number displayed on the 7-segment display when SW01/02/03 are set to 1/1/1.
([U#] [– – –]: # represents the unit No.)
[Setup of outdoor unit for pressure adjustment]
(9) Set SW01/02/03 on the interface P.C. board of the outdoor unit for pressure adjustment to 1/2/2.
(10) As the low-pressure sensor output is displayed on the 7-segment display, adjust the pressure to around
17 psi (0.12 MPa) by slowly closing the gas pipe service valve, with checking pressure data.
(11) Compare the low-pressure sensor outputs of the failed unit with that of the unit for pressure adjustment,
and wait until the two pressure readings become almost the same. After letting the system continue
operating for a while longer, fully close the gas pipe service valve of the unit for pressure adjustment.
[Setup of failed outdoor unit]
(12) When the low-pressure sensor output of the failed outdoor unit falls below 14.5 psi (0.10MPa), fully close
the balance pipe packed valve, and push SW05 on the interface P.C. board to finish the pump-down
operation.
(13) Turn off the power supply to all the outdoor units, and recover the residual refrigerant in the outdoor unit
using a refrigerant recovery device. Be sure to measure the amount of recovered refrigerant. (This is
necessary to determine how much additional refrigerant will be needed after the completion of the repair.)
The outdoor units operating in the pump-
down mode, is selevted to the outdoor
unit for pressure adjustment.
Unit for pressure adjustment
(9)
Set SW01/02/03 to While monitoring low-pressure
1/2/2 to have low sensor output, adjust pressure to
pressure sensor around 17 psi (0.12 MPa) by slowly
output displayed. closing suction gas pipe service valve.
[Ps] [###]
Wait until low-pressure sensor
outputs of failed outdoor unit and
outdoor unit for pressure
adjustment become almost
identical, and, after letting system
continue operating for while longer,
fully close gas pipe service valve.
This is the end of the refrigerant recovery operation.
Set SW01/02/03 of the failed outdoor unit and the outdoor unit for pressure adjustment back to 1/1/1.
[Pd] [1.20]
High-pressure sensor output
(8)
Approx. 10 minutes after system startup,
fully close the suction gas pipe service
valve.
(10)
Push SW04 to have
low-pressure sensor
output displayed
[Ps] [###]
(11)
– 211 –
[Ps] [1.20]
Low-pressure sensor output
(6)
Failed outdoor unit
(7)
When low-pressure sensor output of failed
outdoor unit falls below 14.5 psi (0.10 MPa),
fully close balance pipe packed valve.
Push SW05 to finish pump-down operation.
Turn off power supply to all outdoor units at
source, and recover residual refrigerant in
outdoor unit using refrigerant recovery device.
Measure amount of recovered refrigerant.
(12)
(13)