En-15
7.6.2 Procedures to enable automatic address setting on indoor
units
Check that the rotary switch IU AD on the indoor unit PC board is set to “00”. If it is not set
to “00”, it means the address of that device is not set. (Factory default is “00”).
Turn on the power of the indoor and outdoor units.
• When the system is normal, nothing will be displayed on the 7-segment display.
• When ERROR is displayed, inspect the units.
Use the “MODE/EXIT”, “SELECT”, and “ENTER” buttons on the outdoor unit PC board to
configure settings according to the procedures below.
1: Function setting
(The display when the main power is turned on)
Set to Function mode [F3].
(When [F4] to [F9] are displayed, continue to press
the “SELECT” button until [F3] is displayed.)
Press the “SELECT” button until “11” is displayed.
Press the “ENTER” button for more than 3 seconds.
End
The number of indoor units with normal settings will be
displayed at the first 2 digits of the 7-segment LED display.
The number of indoor units with error will be displayed at
the last 2 digits.
NOTE:
After the “ENTER” button is pressed, the end processing
will occur for about 30 seconds. During this period, the
7-segment will blink.
Automatic address setting for
indoor units
First 2 digits Last 2 digits
7.7. Resistance measurement of transmission cable
(Measure with breaker OFF)
CAUTION
Do not turn on the power if the resistance
between the terminals of the transmission
cable is abnormal. Otherwise, the PC
board may be damaged.
Measure the resistance between 2 termi-
nals of a transmission cable.
(1) Transmission cable connecting
indoor units, outdoor units, and
signal amplifiers
Measure the resistance of the signal
amplifier terminal and the terminal of
the indoor and outdoor units con-
nected farthest away from the device
where terminal resistor is measured.
A value from the table is displayed,
depending on the distance from the
signal amplifier and the device where
the terminal resistor is set.
This value is an estimate.
(2) Transmission cable connecting out-
door units in a refrigerant system
The resistance between the terminals
of the transmission cable is 45-60 Ω.
This value is an estimate.
Distance from terminal resistor
[ft (m)]
0 ~328
(0 ~100)
~656
(~200)
~984
(~300)
~1,312
(~400)
~1,640
(~500)
Approximate resistance (Ω)
0 ~
50
A short circuit somewhere or 2
or more termination resistors are
connected
50
60
70
80
90
100
110
120
130
140
150
160
170
180
190
~
Faulty contact or wiring length over
1,640 ft (500 mm)
1K
~∞
Faulty contact, open circuit, or no
termination resistor
8. PIPE INSTALLATION II
Fig. A Connection system
Fig. B
Outdoor unit
Pressure
gauge
Vacuum
pump
Scale
Pressure regu-
lating valve
Nitrogen
Indoor
unit
Indoor
unit
Service hose
with valve core
Charging
port
Charging
port cap
3-way
valve
Connecting
pipe
Blank cap
Hexagon wrench size
Liquid valve: 4 mm
Gas valve: 8 mm.
Tightening torque [lbf·ft (N·m)]
Model
Liquid valve
Gas valve
Charging
port cap
3-way valve
Blank cap
3-way valve
Blank cap
72/96/
120
6.0 to 7.3
(8.1 to 9.9)
13.3 to 16.2
(18.0 to 22.0)
19.9 to 24.4
(27.0 to 33.0)
16.6 to 20.3
(22.5 to 27.5)
8.4 to 10.3
(11.4 to 14.0)
8.1. Sealing test
CAUTION
Use only nitrogen gas.
Never use refrigerant gas, oxygen, in flammable gas or poisonous gas to pressurize the
system. (If oxygen is used, there is the danger of an explosion.)
Do not apply shock during sealing test.
It can rupture the pipes and cause serious injury.
Do not turn on the power unless all operations are complete.
Do not block the walls and the ceiling until the sealing test and the charging of the
refrigerant gas has been completed.
After connecting the pipes, perform a sealing test.
Recheck that the 3-way valve are closed before performing a sealing test. (Fig. B)
Pour nitrogen gas through both the liquid pipe and the gas pipe.
Pressurize nitrogen gas to 609 psi (4.2 MPa) to perform the sealing test.
Check all flare connection areas and brazed areas.
Then, check that the pressure has not decreased.
Compare the pressures after pressurizing and letting it stand for 24 hours, and check that
the pressure has not decreased.
* When the outdoor temperature changes 9 degrees F (5 degrees C), the test pressure
changes 7.25 psi (0.05 MPa.).
If the pressure has dropped, the pipe joints may be leaking.
If a leakage is found, immediately repair it and perform a sealing test again.
* Decrease the pressure of nitrogen gas before blazing
After completing the sealing test, release the nitrogen gas from both valves.
Release the nitrogen gas slowly.
8.2. Vacuum process
CAUTION
Do not turn on the power unless all operations are complete.
If the system is not evacuated sufficiently, its performance will drop.
Be sure to evacuate the refrigerant system using a vacuum pump.
The refrigerant pressure may sometimes not rise when a closed valve is opened after
the system is evacuated using a vacuum pump. This is caused by the closure of the
refrigerant system of the outdoor unit by the electronic expansion valve. This will not
affect the operation of the unit.
Use a clean gauge manifold and charging hose that were designed specifically for use
with R410A. Using the same vacuum equipment for different refrigerants may damage
the vacuum pump or the unit.
Do not purge the air with refrigerants, but use a vacuum pump to evacuate the system.
• If moisture might enter the piping, follow below. (i.e., if doing work during the rainy
season, if the actual work takes long enough that condensation may form on the
inside of the pipes, if rain might enter the pipes during work, etc.)
• After operating the vacuum pump for 2 hours, pressurize to 7.25 psi (0.05 MPa) (i.e.,
vacuum breakdown) with nitrogen gas, then depressurize down to 500 microns (-100.7
kPa) for an hour using the vacuum pump (vacuum process).
• If the pressure does not reach 500 microns (-100.7 kPa) even after depressurizing for
at least 2 hours, repeat the vacuum breakdown - vacuum process.
After vacuum process, maintain the vacuum for an hour and make sure the pressure
does not rise by monitoring with a vacuum gauge.
9380545309-02.indb 15
9380545309-02.indb 15
2018/12/27 8:39:06
2018/12/27 8:39:06
