Mitsubishi Electric MSZ-FH15NA Service Manual download pdf (Page 29)

D How to check miswiring and serial signal error

MUZ-09/12

NOTE: Refer to the outdoor unit service manual.

Turn OFF inverter-controlled lighting

equipment.

Turn OFF the power supply and then

turn ON again.

Press EMERGENCY OPERATION

switch.

•

Is serial signal

error indicated 6

minutes later?

Yes

Reinstall

either the unit

or the light

away from

each other.

Attach a ﬁ lter

on remote

control receiv-

ing section

of the indoor

unit.

•

Turn OFF the power supply.

Is there rated voltage in the power supply?

Yes

Turn ON the power supply.

Check the power supply.

Is there rated voltage between the outdoor terminal block S1 and S2?

Check the wiring.

Press EMERGENCY OPERATION switch once.

Does the left lamp of OPERATION INDICATOR

lamp light up? <Conﬁ rmation of the power to

the indoor unit>

Yes

Is serial signal error indicated 6 minutes later?

Yes

Is there any miswiring,

poor contact, or wire

disconnection of the

indoor/outdoor connect-

ing wire?

Yes

Correct them.

Turn OFF the power supply.

Check once more if the indoor/outdoor

connecting wire is not miswiring.

Bridge the outdoor terminal block S2 and

S3.

1. Miswiring may damage indoor electronic control P.C.

board during the operation.

Be sure to conﬁ rm the wiring is correct before the opera-

tion starts.

Turn ON the power supply.

Does the LED on the inverter P.C. board repeat

"3.6-second-OFF and 0.8-second-ON quick blinking"? 3

Yes

(Lighted

or not

lighted)

Replace the inverter P.C. board . 2

2. Be careful of the residual voltage of

smoothing capacitor.

Is there amplitude of 10 to 20 VDC between the indoor terminal block

S2 and S3? <Conﬁ rmation of serial signal>

Yes

Check the wiring

If there are any error of the indoor/outdoor connecting wire:

such as the damage of the wire, intermediate connection,

and/or poor contact to the terminal block, replace the indoor/

outdoor connecting wire.

Is there 2 VDC or less between CN202 (+)

and JPG (GND)(-) on the indoor electronic

control P.C. board?

Yes

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

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

inverter P.C. board is normal, LED blinks 6 times after 3

minutes.

Is there 2 VDC or less between

CN202 (+) and JPG (GND)(-) on

the indoor electronic control P.C.

board?

Is there 2 VDC or less between

CN202A

(+) and JPG (GND)(-)

on the indoor electronic control P.C.

board?

Replace the indoor elec-

tronic control P.C. board.

No Yes No

Yes

Is the bus-bar voltage of the inverter P.C. board normal?

(Refer to "TEST POINT DIAGRAM AND VOLTAGE" in the outdoor service manual.)

Yes

Check of power supply.

(Refer to the outdoor

service manual.)

Turn OFF the power supply.

Remove the bridge between the outdoor terminal block S2 and S3.

Turn ON the power supply.

Yes

Replace the indoor power

P.C. board.

Is there rated voltage between the indoor terminal block S1 and S2?

<Conﬁ rmation of power voltage>

OBH683

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Mitsubishi Electric MSZ-FH15NA Service Manual Page 29

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