Mitsubishi Electronics MSH-18NV, MSH-24NV service manual MSH-07NV MSH-09NV MSH-12NV

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

MSH-07NV MSH-09NV MSH-12NV

Start

1. Turn OFF power supply.

❈ 1 Short circuit of JPG and JPS on the

MSH-18NV

2. Turn ON power supply.

indoor electronic control P.C. board enables self-check to be displayed in 3

Repair wiring.

3. Press EMERGENCY OPERATION switch.

seconds.

Serial signal error is indicated.

3 min. later, when relay 52C turns ON, what self-check result is (0.5-sec.ON,2.5-sec.OFF)displayed on OPERATION INDICATOR lamp on indoor unit? ❈ 1

Mis-wiring is indicated.(0.5-sec.ON, 0.5-sec.OFF)

Yes

Is there mis-wiring, poor contact, or wire disconnection?

No

1.Turn OFF power supply and disconnect in-out connecting wire on indoor side.

2.Short-circuit between indoor terminal block N and 3

3.Turn ON power supply and press EMERGENCY OPERATION switch.

Is there 20V DC between both ends of R132 when	No
relay (52C) turns ON?
( By tester, the stylus is between 0 ~ 20V. )

Yes

•Turn OFF power supply.

•Connect ON in-out connecting wire. •Turn ON power supply.

3 minutes later, when EMERGENCY OPERATION switch is pressed	No
and 52C relay turns ON, is there AC 220-240V between outdoor
terminal block 2 - N ?

Yes

Under the same condition as 3 minutes later, when

Replace the indoor electronic control P.C. board.

Rectify in-out connecting wire.

EMERGENCY OPERATION switch is pressed and 52C relay turns on, is there DC 5V between

J8 + -J7 – ?

Yes

No

Check and rectify fuse and varistor on out- door DEICER P.C. board.

Under the same condition as 3 minutes later, when

EMERGENCY OPERATION switch is pressed and No 52C relay turns on, is there DC 10V between both

ends of R601?

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

Yes

Rectify in-out connecting wire.

Replace the outdoor DEICER P.C. board.

53