Mitsubishi Electric MSZ-GA50VA Service Manual page 21

• When unit cannot operate neither by the remote controller nor by EMERGENCY OPERATION switch.
Indoor unit does not operate.
• When OPERATION INDICATOR lamp flashes ON and OFF in every 0.5-second.
Outdoor unit does not operate.
How to check mis-wiring and serial signal error (when outdoor unit does not work)
D
Outdoor electronic control P.C. board
(Parts side)
LED2 LED1
Blinking
A
· Turn OFF inverter-controlled lighting
equipment.
· Turn OFF the power supply and then
turn ON it again.
· Press EMERGENCY OPERATION
switch.
Is serial signal
No
error indicated
6 minutes later?
Yes
B
Turn OFF the power supply.
Is there rated voltage of
230V AC in the power
supply?
Turn ON the power supply.
Is there 230V AC between
outdoor terminal block S1 and
S2?
Press EMERGENCY OPERATION switch.
Does the left lamp of OPERATION INDICATOR
lamp light up?
<Confirmation of the power to the indoor unit>
Is the self-check of the indoor unit displayed 6
minutes after?
Serial signal error display
The left lamp of
OPERATION
INDICATOR lamp
blinks quickly.
Turn OFF the power supply.
Check once more if the indoor/outdoor
B
connecting wire is not mis-wiring.
Short-circuit outdoor terminal block S2 and
S3.(The indoor/outdoor connecting
wire can be kept connected.)
Turn ON the power supply of the outdoor unit.
Does the LED1 on the outdoor electronic
control P.C. board repeat quick blinking
"3.6-second-OFF and 0.8-second-ON"?
Remove the short-circuit between
outdoor terminal block S2 and S3.
Is there amplitude of 10 to 20V DC
between outdoor terminal block S2
and S3?
· Reinstall
either the
unit or the
light each
other away.
· Attach a filter
on receiving
Replace the indoor electronic control P.C. board.
section of
the indoor
Be sure to release the failure-mode
unit.
recall function after checking.
As for outdoor unit MUZ type, refer to service manual OB389.
As for outdoor unit MXZ type, refer to service manual OB377.
No
Check the power
supply.
Yes
No
Check the wiring.
Yes
No
Yes
No
Yes
A
W1. If short-circuiting with the indoor/outdoor unit connecting
wire kept connected, make sure the wire is correctly
W1
connected,otherwise the board may be broken.
No
(Lighting
or
not lighting)
Yes
Is there any error of the
indoor/outdoor connecting wire,
such as the damage of the wire,
intermediate connection, poor
No
contact to the terminal block?
Yes
21
Is there any mis-wiring,
poor contact, or wire
Yes
Make them sure.
disconnection of the
indoor/outdoor
connecting wire?
No
Replace the outdoor electronic
control P.C. board.
W2
W2 Be careful to the residual
voltage of smoothing capacitor.
Replace the
Yes
indoor/outdoor
connecting.
No