How To Check Mis-Wiring - Mitsubishi Electric MU-GA50VB Service Manual

Compressor and/or outdoor fan motor doesn't stop.
B
Check of outdoor unit
1 Turn OFF the power supply.
2 After 30 seconds, turn ON the power supply again.
3 Operate the unit in COOL mode by pressing the
EMERGENCY OPERATION switch.
4 Operate the unit for 1 minute or more and stop it by
pressing the EMERGENCY OPERATION switch again.
After 30 seconds,
does compressor stop?
After 30 seconds, does
outdoor fan motor stop?
When OPERATION INDICATOR lamp flashes ON and OFF in every 0.5-second.
Outdoor unit doesn't operate.

How to check mis-wiring

C
Make them sure.
1. Turn OFF the power supply (indoor/ outdoor unit) and disconnect indoor and outdoor
connecting wire at the terminal block 3 of the indoor unit.
2. Short-circuit terminal block N-3 of indoor unit by lead wire.
3. Turn ON the power supply (indoor unit) and press once EMERGENCY OPERATION switch.
MU-GA80VB
Is there 230V AC between
No
A1-A2 on the compressor
contactor (52C)?
Yes
Ok
Replace the
deicer P.C. board.
No
Replace the
deicer P.C. board.
Yes
Ok
MU-GA80VB
Start
• Turn ON the power supply. (indoor/ outdoor unit)
• Press once EMERGENCY OPERATION switch.
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
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)
Disconnect the lead wire that terminal
block N-3 of the indoor unit is short-circuited.
• Connect ON indoor/ outdoor connecting
wire.
Turn ON the power supply. (outdoor unit)
Is there 230V AC between L-N
on the outdoor terminal block?
Yes
Is there 5V DC between J101 + -J401 -
on the deicer P.C. board?
Refer to page 29.
Yes
During EMERGENCY OPERATION, is there
10V DC between both ends of R601on the
deicer P.C. board? Refer to page 29.
(By tester, the stylus is between 5 ~10V.)
Yes
Replace the deicer P.C. board.
Is there 230V AC between
No
2/T1 on the compressor
contactor (52C) and N on
the outdoor terminal block?
Yes
Replace the compressor
contactor (52C).
w Short circuit of JPG and JPS on the indoor electronic control
P.C. board enables self -check to be displayed in 3 seconds.
No
Replace the indoor electronic
control P.C. board.
No
Check the outdoor power supply
and connection of wiring.
No
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 29.
27
No
Rectify the connecting
wire.
Yes
As for indoor unit,
refer to service
manual OB369.