Mitsubishi Electronics MUZ-GB50VA service manual Parts side

•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 doesn’t operate.

H How to check mis-wiring and serial signal error (when outdoor unit does not work)

Turn OFF the power supply.

Is there rated voltage in	No
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 outdoor electronic control P.C. board is normal,

LED blinks 6 times after 3 minutes.

Does the LED on the outdoor electronic

No

Replace the outdoor electronic

control P.C. board repeat "3.6-second-OFF

control P.C. board. W2

Outdoor electronic control P.C. board

and 0.8-second-ON quick blinking"? W3

(Lighted

(Parts side)

or not

W2 Be careful to the residual

LED2 LED1

Yes

lighted)

voltage of smoothing capacitor.

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,

Yes

Replace the

Turn ON the power supply.

Lighted Blinking

such as the damage of the wire,

indoor/outdoor

Is there amplitude of 10 to 20V DC

No

intermediate connection, poor

connecting wire.

between outdoor terminal block S2

contact to the terminal block?

A

and S3? <Confirmation of serial

signal>

· Turn OFF inverter-controlled lighting

No

equipment.

Yes

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

· Press EMERGENCY OPERATION						Is there any error of the
switch.				Is there rated voltage between		indoor/outdoor connecting wire,		Yes	Replace the
			· Reinstall	indoor terminal block S1 and S2?	No	such as the damage of the wire,			indoor/outdoor
				<Confirmation of power voltage>		intermediate connection, poor
			either the						connecting wire.
						contact to the terminal block?
			unit or the	Yes
Is serial signal			light each				No
		No	other away.
error indicated			· Attach a filter
6 minutes later?			on remote
			control
			receiving	Replace the indoor electronic control P.C. board.
	Yes		section of	Be sure to release the failure-mode
			the indoor
				recall function after checking.
B			unit.	Refer to indoor unit service manual.

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