■ 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 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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