Test Run; Before Test Run; Using Remote Controller; Using Sw4 In Outdoor Unit - Mitsubishi Electric MXZ-8A140VA Installationshandbuch

7. Electrical work
WIRING SPECIFICATIONS
(OUTDOOR-BRANCH BOX CONNECTING CABLE)
Cross section of cable Wire size (mm
Round
2.5
Flat
2.5
Flat
1.5
Round
2.5
*1 : Power supply cords of appliances shall not be lighter than design 245 IEC or 227
IEC.
*2 : In case that cable with stripe of yellow and green is available.
*3 : In case of regular polarity connection (S1-S2-S3), wire size is 1.5 mm
*4 : In case of regular polarity connection (S1-S2-S3).
*5 : In the flat cables are connected as this picture, they can be used up to 55 m.
Be sure to connect the outdoor-branch box/indoor-branch box connecting cables directly to the units (no intermediate connections).
Intermediate connections can lead to communication errors if water enters the cables and causes insufficient insulation to ground or a poor electrical contact at the
intermediate connection point.
(If an intermediate connection is necessary, be sure to take measures to prevent water from entering the cables.)

8. Test run

8.1. Before test run

s After completing installation and the wiring and piping of the indoor and
outdoor units, check for refrigerant leakage, looseness in the power supply
or control wiring, wrong polarity, and no disconnection of one phase in the
supply.
s Use a 500-volt M-ohm tester to check that the resistance between the power
supply terminals and ground is at least 1 MΩ Ω Ω Ω Ω .
s Do not carry out this test on the control wiring (low voltage circuit) termi-
nals.
Warning:
Do not use the air conditioner if the insulation resistance is less than 1 MΩ Ω Ω Ω Ω .
Insulation resistance
After installation or after the power source to the unit has been cut for an extended
period, the insulation resistance will drop below 1 MΩ due to refrigerant accumulat-
ing in the compressor. This is not a malfunction. Perform the following procedures.
1. Remove the wires from the compressor and measure the insulation resistance of
the compressor.
2. If the insulation resistance is below 1 MΩ, the compressor is faulty or the resist-
ance dropped due the accumulation of refrigerant in the compressor.
8.2. Test run

8.2.1. 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.
2 ) Number of wires
Clockwise : S1-S2-S3
3
* Pay attention to stripe of yellow and green
Not applicable
3
(Because center wire has no cover finish)
4 From left to right : S1-Open-S2-S3
Clockwise : S1-S2-S3-Open
4
*Connect S1 and S3 to the opposite angle
2
.
Polarity
(3C Flat cable × 2)
S1 S2 S3
*6 : Mentioned cable length is just a reference value.
It may be different depending on the condition of installation, Humidity or materi-
als, etc.
3. After connecting the wires to the compressor, once operating, measure the insu-
lation resistance again.
• The insulation resistance drops due to accumulation of refrigerant in the com-
pressor. The refrigerant collected in the compressor is discharged by operating
at once.
4. If the insulation resistance rises above 1 MΩ, the compressor is not faulty.
Caution:
• The compressor will not operate unless the power supply phase connection
is correct.
s The followings must be checked as well.
• The outdoor unit is not faulty. LED on the control board of the outdoor unit flash
when the outdoor unit is faulty.
• Both the gas and liquid stop valves are completely open.

8.2.2. Using SW4 in outdoor unit

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
connecting wires. If it aims at detection of any erroneous connection, be
sure to carry out the test run from remote controller with reference to "8.2.1
Using remote controller."
SW4-1 ON
Cooling operation
SW4-2 OFF
SW4-1 ON
Heating operation
SW4-2 ON
* After performing the test run, set SW4-1 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 SW4-2 during
the test run. (To change the test run operation mode during the test run, stop
the test run by DIP switch SW4-1. After changing the test run operation mode,
resume the test run by switch SW4-1.)
When a test run is started by "Using SW4 in outdoor unit", even if it carries
out stop instructions by remote controller, outdoor unit does not stop (a
test run is not ended). In this case, please set SW4 in outdoor unit to off.
L (m)*6
(50)
*2
Not applicable
*5
(45)
*3
(55)
*4
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