II - 3
(3) Safety check
Insulation resistance check
Perform the following procedure to check the insulation up until the unit power terminal block.
Turn off the main power supply of the indoor and outdoor units.
Turn off the power switch in the terminal box of the outdoor unit.
Connect the insulation tester between each of the power terminals of the R phase, O phase, and S phase and the
ground terminal on the power terminal block (TB1) in the terminal box, and take measurements. (Figure 1)
If a resistance check is required on the outdoor unit side, turn on the power switch in the terminal box, and take
measurements.
* Measurement criterion: 1 M
Ω
or more
(2) Fuel tube connector leak check
Open the liquid tube cock.
Use a gas leak detector (Figure 2), soap solution, or the like to check that there is no leak from the fuel tube con-
nector of the outdoor unit.
(4) Indoor/outdoor control wire connection con
fi
rmation
Check the indoor/outdoor control wire connection regardless of whether there is a warning or not. Before performing the
check, turn off the power of all devices (including controllers) that are connected to the indoor/outdoor control wire.
1. Ground fault check
1-1
Measure the resistance between one end of the indoor/outdoor control wire and
the point of ground screw, as well as the resistance between the other operating
line end and the point of ground screw. Are both measured resistance values in
M
Ω
unit (in
fi
nite)?
Yes 2-1
No 1-2
1-2 Because the indoor/outdoor control wiring has a ground fault, search for the location of the
ground fault.
2. Short circuit check
2-1
Measure the resistance between the indoor/outdoor control wires on the terminal
board of the outdoor unit.
The measured resistance value is around 75 to 100
Ω
?
When setting multiple "ON (SHORT)" to switches with terminal resistor, the
resistance value mentioned above is 1 over number of units. *1
Yes 3-1
No 2-2
2-2
If the wiring has a short circuit, search for the location of the short circuit on the indoor/
outdoor control wire.
If it is open, check the terminal resistor of outdoor board, and check the wiring from out-
door board to outdoor terminal board.
3. Wire break or dis-
connection check
3-1
Measure the resistance between the indoor/outdoor control wires on the boards
of all devices that are connected to the control wires.
Any location with measured resistance values in M
Ω
units (in
fi
nite)?
Yes 3-2
No 4-1
3-2 Because the wiring has a break, search for the location of the break.
4. Shield wire check
4-1 A shield wire is used as an indoor/outdoor control wire?
Yes 4-2
No 5-1
4-2 Only one end of the shield wire is grounded?
Yes 5-1
No 4-3
4-3 Ground only one end of the shield wire.
5. Others
5-1 Check total wire length and the number of branch connections and connected units.
* Terminal resistor is basically “ON (SHORT) for one unit only, but depending on the installation status can be set to
“ON (SHORT)” for up to 3 units.
Figure 2
Figure 1
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