Mitsubishi Electronics MSZ-A12NA, MSY-A24NA How to check mis-wiring and serial signal error

•When unit cannot operate neither by the remote controller nor by EMERGENCY OPERATION switch. Indoor unit does not operate.

•When OPERATION INDICATOR lamp flashes ON and OFF in every 0.5-second. Outdoor unit does not operate.

DHow to check mis-wiring and serial signal error

Turn OFF the power supply.

Is there rated voltage AC	No
in the power supply?
Yes

Turn ON the power supply.

Check the power supply.

Is there rated voltage between

No

Check the wiring.

outdoor terminal block S1 and

S2?

Yes

Press EMERGENCY OPERATION switch once.

Does the left lamp of OPERATION INDICATOR

lamp light up?

No

<Confirmation of the power to the indoor unit>

Yes

Is there any mis-wiring,

Is serial signal error indicated 6 minutes later?

No

poor contact, or wire

Yes

disconnection of the

Make them correct.

indoor/outdoor

Yes

connecting wire?

No

A

Turn OFF the power supply.

Check once more if the indoor/outdoor

B

connecting wire is not mis-wiring.

Short-circuit outdoor terminal block S2 and

W1. Mis-wiring may damage indoor electronic control

S3.

P.C. board during the operation.

W1

Be sure to confirm the wiring is correct before the

operation starts.

W3.Be sure to check this within 3 minutes after turning

ON. After 3 minutes, LED blinks 6 times. Even when

Turn ON the power supply.

the inverter P.C.board or the outdoor electronic control

P.C.board is normal, LED blinks 6 times after

3 minutes.

(Except for outdoor unit of multi system type)

Does the LED on the inverter P.C. board

No

Replace the inverter P.C. board or

or the outdoor electronic control P.C.board

the outdoor electronic control P.C.board.

repeat "3.6-second-OFF and 0.8-second-ON (Lighted or

W2

quick blinking"? W3

not lighted)

W2 Be careful to the residual

Yes

voltage of smoothing capacitor.

A

·Turn OFF inverter-controlled lighting equipment.

·Turn OFF the power supply and then turn ON again.

·Press EMERGENCY OPERATION switch.

Turn OFF the power supply.
Remove the short-circuit between		Is there any error of the
outdoor terminal block S2 and S3.		indoor/outdoor connecting wire,
Turn ON the power supply.
		such as the damage of the wire,
Is there amplitude of 10 to 20V DC
	No intermediate connection, poor
between outdoor terminal block S2
and S3? <Confirmation of serial		contact to the terminal block?
signal>			No
Yes
		Is there any error of the
Is there rated voltage between
		indoor/outdoor connecting wire,
indoor terminal block S1 and S2?		such as the damage of the wire,

Yes

Yes

Replace the indoor/outdoor connecting wire.

Replace the

Is serial signal	No
error indicated
6 minutes later?

·Reinstall either the unit or the light each other away.

·Attach a filter on remote control

<Confirmation of power voltage>	intermediate connection, poor
	contact to the terminal block?
	No
Yes	No

indoor/outdoor connecting wire.

Yes

B

receiving section of the indoor unit.

Replace the indoor electronic control P.C. board.

Be sure to release the failure-mode recall function after checking.

Refer to outdoor unit service manual.

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