Vermont Casting MSZ-D36NA, MSZ-D30NA, MSY-D36NA How to check miswiring and serial signal error

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

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

D How to check miswiring and serial signal error

Turn OFF the power supply.
Is there rated voltage AC in
		Check the power supply.
the power supply?	No

Yes

Turn ON the power supply.

Is there rated voltage between outdoor terminal block S1 and

S2?No

Yes

Press EMERGENCY OPERATION switch once.

Does the left lamp of OPERATION INDICATOR lamp light up? <Confirmation of the power to the indoor unit>

Yes

Is serial signal error indicated 6 minutes later?

Yes

Check the wiring.

No

Is there any miswiring, poor contact, or wire disconnec-

No tion of the indoor/outdoor Yes Correct them. connecting wire?

Is fuse (F65) broken? No

A

•Turn OFF inverter-controlled lighting equipment.

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

•Press EMERGENCY OPERATION switch.

		A
		Turn OFF the power supply.
B		Check once more if the indoor/outdoor
		connecting wire is not miswiring.		1. Miswiring may damage indoor electronic control
		Short-circuit outdoor terminal block S2		P.C. board during the operation.
		and S3. 1		Be sure to confirm the wiring is correct before
				the operation starts.
		Turn ON the power supply.
	Does the LED on the inverter P.C. board or
					Replace the inverter P.C. board or the
	the outdoor electronic control P.C. board
					outdoor electronic control P.C. board.
	repeat "3.6-second-OFF and 0.8-second-			No
					2
	ON quick blinking"?			(Lighted
			Yes	or not	2. Be careful to the residual
				lighted)	voltage of smoothing capacitor.

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

Is serial signal error indicated 6 minutes later?

Yes

B

No

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

•Attach a filter on remote control receiv- ing section of the indoor unit.

indoor terminal block S1 and S2?		No	such as the damage of the wire,			Replace the indoor/out-
					Yes	door connecting wire.
<Confirmation of power voltage>			intermediate connection, poor
	Yes		contact to the terminal block?
				No

Replace the indoor electronic control P.C. board.

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

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