Pump Down; Electrical Work; Caution - Mitsubishi Electric CITY MULTI PUMY-71 Manuel D'installation

7.7. Pump down

Before removing air conditioners for transfer to another location, always
close the stop valve (for both liquid and gas pipes) located at the outdoor
unit, then remove the indoor and outdoor units. At this time, the refriger-
ant in the indoor unit will be discharged. To minimize the refrigerant dis-
charged, a pump down operation is required. This operation collects the
refrigerant present inside the air conditioner and sends it into the heat
exchanger located in the outdoor unit.
Pump down procedure
1 Operate all indoor units in cooling mode and check that the operation
mode has changed to "COOL". (Set the units so that cooling opera-
tion mode is activated during the pump down operation (when the
TEST RUN button is pressed).)
2 Connect a gauge manifold valve (with pressure gauge) to the stop
valve of the gas pipe, to enable measurement of refrigerant pres-
sure.
3 Check that the operation is stopped and switch the outdoor service
switch [SW5-3] (pump down switch) from OFF to ON.
4 Press the outdoor service switch [SW3-1,2] (test run switch) to start
operation in cooling mode.
5 After the cooling operation has been carried out for approximately
five minutes, close the stop valve on the liquid pipe, with the cooling
operation still ON. (Pump down operation will start.)
6 When the reading of the pressure gauge reaches 0 to 0.1 MPa (0 to
2
1 kg/cm G) or when approximately 5 minutes have elapsed following
the start of the pump down operation, fully close the stop valve on
the gas pipe and stop the air conditioner by pressing the outdoor
service switch [SW3-1,2] immediately.

8. Electrical work

8.1. Caution

1 Follow ordinance of your governmental organization for technical
standard related to electrical equipment, wiring regulations and guid-
ance of each electric power company.
Warning:
Be sure to have authorized electric engineers do electrical work
using special circuits in accordance with regulations and this in-
stallation manual. If the power supply circuit has a lack of capacity
or electrical work deficiency, if may cause an electric shock or fire.
2 Wiring for control (hereinafter referred to as transmission line) shall
be (5cm or more) apart from the power source wiring so that it is not
influenced by electric noise from the power source wiring. (Do not
insert the transmission line and power source wire in the same con-
duit.)
3 Be sure to provide designated grounding work to the outdoor unit.
Caution:
Be sure to put outdoor unit to earth. Do not connect the earth line
to any gas pipe, water pipe, lightning rod or telephone earth line. If
the earth is incomplete, it may cause an electric shock.
4 Give some allowance to the wiring for the electrical part box of the
indoor and outdoor units, because the box is sometimes removed at
the time of service work.
5 Never connect the main power source to the terminal block of the
transmission line. If connected, electrical parts will be burnt out.
6 Use 2-core shield cable for the transmission line. If transmission lines
of different systems are wired with the same multiplecore cable, the
resultant poor transmitting and receiving will cause erroneous op-
erations.
7 Switch the outdoor service switch [SW5-3] from ON to OFF.
8 Remove the gauge manifold valve and put the cap back onto each
stop valve.
Notes:
1 Never carry out pump down operation if the amount of refriger-
ant inside the indoor unit is larger than the amount of charge-
less refrigerant.
Carrying out a pump down operation when the amount of refrig-
erant exceeds the amount of charge-less refrigerant will cause
an extreme pressure rise and may result in an accident.
2 The service switch [SW5-3] can only be changed over while the
compressor is stopped. If you have changed over this service
switch even if the compressor is still in operation, stop the op-
eration, then retry to change it over.
Do not continue to operate for a long time with the switch [SW5-
3] set to ON.
Make sure to switch it to OFF after pump down is completed.
3 Test run can be carried out when the test run switch [SW3-1] is
ON. Switch [SW3-2] is used to start and stop operation.
4 Time required for a pump down operation is three to five min-
utes after the stop valve on the liquid pipe has been closed. (It
depends on the ambient temperature and amount of refrigerant
inside the indoor unit.)
5 Ensure that the reading of the pressure gauge does not drop
below 0 MPa (0 kg/cm 2 G). If it drops 0 MPa (0 kg/cm
vacuum is created), air will be drawn into the unit if there are
any loose connections.
6 Even if the reading of the pressure gauge does not drop below 0
MPa (0 kg/cm 2 G), always stop the pump down operation within
approximately five minutes after the stop valve on the liquid pipe
has been fully closed.
Outdoor unit
Transmission line
(2-core shielded cable)
Transmission line
(2-core shielded cable)
Outdoor unit
Multiple-core
cable
2 G) (i.e.
Indoor unit
Remote controller
Indoor unit
Remote controller
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