Mitsubishi Electric MSC-C07TV Service Manual page 56

How to check mis-wiring and serial signal error
E
Outdoor unit doesn't operate.
Yes
Make them sure.
1. Turn OFF the power supply
2. Short-circuit between indoor terminal block N and 3.
3. Turn ON the power supply
Start
Turn OFF the power supply(indoor/outdoor unit).
Is the outdoor unit "MUH" type?
Yes
•Turn ON the power supply(indoor/outdoorunit).
•Press once EMERGENCY OPERATION switch.
3 min. later, what self-check result is
displayed on OPERATION INDICATOR
w
lamp on indoor unit? 2
Mis-wiring is indicated.
(0.5-sec. ON, 0.5-sec. OFF)
Is this mis-wiring, poor contact,
or wire disconnection?
No
and disconnect in-out connecting wire on indoor side.
(indoor/outdoor unit)
and press once EMERGENCY OPERATION switch.
(indoor unit)
Is there 20V DC between both ends of
R132 on the indoor electronic control P.C.
board ?
( By tester, the stylus is between 0 ~ 20V. )
Yes
•Turn OFF the power supply(indoor unit).
•Connect ON in-out connecting wire.
Turn ON the power supply(outdoor unit).
Is there 230V AC between outdoor
L N
terminal block - ?
Yes
-
Is there 5V DC between J8
(Refer to page 58.)
Yes
Turn ON the power supply(indoor unit).
During EMERGENCY OPERATION,
is there 10V DC between both ends
of R601? (Refer to page 58.)
(By tester, the stylus is between 5 ~10V)
Yes
Replace the DEICER P.C. board.
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1 Set the switch(SW2-2) on the indoor electronic control P.C.
board to MU type, when the outdoor unit is MU type.
If the setting is MUH type, the unit does not work.
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2 Short circuit of JPG and JPS on the indoor electronic control
P.C. board enables self -check to be displayed in 3 seconds.
No
Serial signal error is indicated.
(0.5-sec. ON, 2.5-sec. OFF)
No
Replace the indoor electronic
control P.C. board.
Check the outdoor power supply,
No
power supply cord and
connection.
No
+
-J9 ?
Replace the DEICER P.C. board.
Make the wiring between CN730
No
on the DEICER P.C. board and
outdoor terminal block correct.
(Refer to page 58.)
56
Set the switch(SW2-2) on the indoor electronic
control P.C. board to MU type. (Refer to page 46.)
Does the unit operate?
No
Follow the chart
on page 49.
w
1
Yes
Ok