Using Remote Controller; Using Sw3 In Outdoor Unit - Mitsubishi Electric CITY MULTI PUMY-P YHM-Serie Installationshandbuch

7. Test run
7.2. Test run

7.2.1. Using remote controller

Refer to the indoor unit installation manual.
• Be sure to perform the test run for each indoor unit. Make sure each indoor
unit operates properly following the installation manual attached to the unit.
• If you perform the test run for all indoor units at once, you cannot detect any
erroneous connection, if any, of the refrigerant pipes and the connecting wires.
* The compressor operation is not available for 3 minutes at least after the
power is supplied.
• The compressor can emit noise just after turn on the power supply or in case
of low outside air temperature.
About the restart protective mechanism
Once the compressor stops, the restart preventive device operates so the compres-
sor will not operate for 3 minutes to protect the air conditioner.
7.3. Refrigerant collecting (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 refrigerant in the indoor unit will be dis-
charged. To minimize the refrigerant discharged, 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 operation 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 pressure.
3 After setting the outdoor service switch SW3-2 to OFF, set the switch SW3-1 to
ON. (The unit will start in cooling mode.)
4 After the cooling operation has been carried out for approximately five minutes,
set the outdoor service switch SW2-4 (pump down switch) from OFF to ON.
5 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 1 kg/cm
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 condi-
tioner by setting the switch SW3-1 to OFF immediately.
All manuals and user guides at all-guides.com

7.2.2. Using SW3 in outdoor unit

Note:
In case of the test run from outdoor unit, all indoor units operate. Therefore,
you can not detect any erroneous connection of refrigerant pipes and the con-
necting wires. If it aims at detection of any erroneous connection, be sure to
carry out the test run from remote controller with reference to "7.2.1 Using
remote controller."
* After performing the test run, set SW3-1 to OFF.
• A few seconds after the compressor starts, a clanging noise may be heard from the
inside of the outdoor unit. The noise is coming from the check valve due to the small
difference in pressure in the pipes. The unit is not faulty.
The test run operation mode cannot be changed by DIP switch SW3-2 during
the test run. (To change the test run operation mode during the test run, stop
the test run by DIP switch SW3-1. After changing the test run operation mode,
resume the test run by switch SW3-1.)
7 Set the outdoor service switch SW2-4 from ON to OFF.
8 Remove the gauge manifold valve and put the cap back onto each stop valve.
Note:
1 Never carry out pump down operation if the amount of refrigerant inside
2 Do not continue to operate for a long time with the switch SW2-4 set to ON.
3 Test run can be carried out when the test run switch SW3-1 is ON. Switch
4 Time required for a pump down operation is three to five minutes after the
5 Ensure that the reading of the pressure gauge does not drop below 0 MPa
2 G)
6 Even if the reading of the pressure gauge does not drop below 0 MPa (0 kg/
SW3-1 ON
Cooling operation
SW3-2 OFF
SW3-1 ON
Heating operation
SW3-2 ON
the indoor unit is larger than the amount of charge-less refrigerant.
Carrying out a pump down operation when the amount of refrigerant ex-
ceeds the amount of charge-less refrigerant will cause an extreme pres-
sure rise and may result in an accident.
Make sure to switch it to OFF after pump down is completed.
SW3-2 is used to operating mode selection. (On: Heating, OFF: Cooling)
stop valve on the liquid pipe has been closed. (It depends on the ambient
temperature and amount of refrigerant inside the indoor unit.)
2 2
(0 kg/cm G). If it drops 0 MPa (0 kg/cm
drawn into the unit if there are any loose connections.
cm 2 G), always stop the pump down operation within approximately five min-
utes after the stop valve on the liquid pipe has been fully closed.
G) (i.e. vacuum is created), air will be
11