■ If the self-diagnostics function fails to operate
<Checking the indoor and outdoor units>
■ Checking the indoor unit
■ Checking the outdoor unit
■ Checking the serial communications
● Using the TEST/T-RUN terminals
Check the indoor unit.
Is the fuse blown?
ControlNo. Check items (unit operation)
Replace the controller.
Replace the circuit
board or the fuse.
• No indicators illuminate and the
indoor fan does not turn.
• Check the power voltage.
T-RUN : Test run (compressor and fan motor turn ON.)
TEST/MV : Compresses time to 1/60th (accelerates
operation by 60 times faster than normal).
Fully opens the electric expansion valve.
Set operation selector of indoor unit main
body to DEMO and start operation using the
remote controller.
● If there are no problems with the above, then check the outdoor unit.
1 • The rated voltage must be present between inter-unit cables 1 and 2.
• Connect a 5 kΩ resistor between inter-unit cables 2 and 3. When the
voltage at both ends is measured, approximately 12–15 V DC must
be output and the needle must fluctuate once every 8 seconds.
In addition, insert an LED jig and check that the LED flickers once
every 8 seconds.
ControlNo. Check items (unit operation)
Short-circuit terminals 2 and 3 on
the indoor unit 3P terminal block.
Initial self-
diagnostics
Probable location of malfunction
Short-circuit terminals 2 and 3 on
the indoor unit 3P terminal block.
Apply the rated voltage between outdoor
unit terminals 1 and 2.
● If there are no problems with the above, then check the indoor unit.
● Turn the power OFF before performing short circuiting work.
● During the self-diagnostics check, the check results are the first indication when the operation switch is moved to OFF while the
indicators are flashing after power ON → DEMO (5 seconds) → ON.
● So that the check can be made quickly, indicators flash at first communication after power ON.
● Before performing the above checks, perform DEMO operation, and check that AC 220 V is output to terminals 1 and 2.
If it is not output, there is a failure related to the indoor unit power.
1 • The control panel LED (red) must illuminate.
Short-circuit the outdoor unit COM terminal
to the T-RUN terminal.
2 • The compressor and fan motor must turn ON.
Normal
Blown
TEST/T-RUN terminals
TEST/MV T-RUN COM
→ Control 1
No change Indoor unit circuit board failure
Outdoor unit circuit board failure
Failure (open circuit, contact failure, etc.)
in the inter-unit cable
Indoor unit circuit board failure
Change: (1) and (3) illuminate,
and (2) flashes.
(1) illuminate
Change: (1) and (3) illuminate,
and (3) flashes.
Change: (1) and (3) illuminate,
and (2) flashes.
Change: (1) illuminates
(1) and (3) illuminate,
and (2) flashes.
→ Control 2
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