Mitsubishi Electronics MSH-A18ND service manual How to check mis-wiring

When OPERATION INDICATOR lamp flashes ON and OFF in every 0.5-second.

Outdoor unit doesn’t operate.

D How to check mis-wiring

w Short circuit of JPG and JPS on the indoor electronic control P.C. board enables self -check to be displayed in 3 seconds.

Start

Correct them.

•Turn ON the power supply. (outdoor unit)

•Press EMERGENCY OPERATION switch once.

After 3 minutes, mis-wiring is indicated (0.5-second ON, 0.5-second OFF) on OPERATION INDICATOR

lamp on indoor unit.w

Yes	Is this mis-wiring, poor contact,
	or wire disconnection?
	No

1.Turn OFF the power supply (outdoor unit) and disconnect indoor and outdoor connecting wire 3 on indoor side.

2.Short-circuit terminal block N-3by lead wire.

3.Turn ON the power supply (outdoor unit) and press EMERGENCY OPERATION switch once.

Is there 20V DC between both ends of

PS132 on the indoor electronic control P.C. No board ?

( By tester, the stylus is between 0 ~ 20V. )

Yes

•Turn OFF the power supply. (outdoor unit)

•Connect ON indoor/ outdoor connecting wire.

Replace the indoor electronic control P.C. board.

Turn ON the power supply. (outdoor unit)

Is there 5V DC between J205 + -J101 -

/ J101 + -J401 - on the deicer P.C. board?

Yes

During EMERGENCY OPERATION, is there 10V DC between both ends of R601 on the deicer P.C. board?

(By tester, the stylus is between 5 ~10V.)

Yes

No	Replace the deicer P.C. board.
No	Make the wiring between CN730
	on the deicer P.C. board and
	outdoor terminal block correct.

Replace the deicer P.C. board.

Refer to outdoor unit service manual.

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