How To Check Mis-Wiring And Serial Signal Error - Mitsubishi Electric MXZ-2B20NA Service Manual

• 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

LED indication
for communication status
Communication status is indicated
by the LED.
Unit status
Blinking: normal communication
Lighting: abnormal communication or
not connected
Pattern 1 and 2 is repeatedly displayed
alternately. Each pattern is displayed for
15 seconds.
NOTE: "Lighting" in the table below does not
indicate abnormal communication.
MXZ-2B20NA
MXZ-2B20NA -
1
Outdoor electronic control P.C. board
(Parts side)
LED3 LED2 LED1
Blinking
Pattern
LED 3 LED 2
Unit B
1 Lighting
status
2 Goes out Lighting
A
· Turn OFF inverter-controlled lighting
equipment.
· Turn OFF the power supply and then
turn ON 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 in
the power supply ?
Turn ON the power supply.
Is there rated voltage between
outdoor terminal block S1 and
S2 ?
Press EMERGENCY OPERATION switch once.
Does the left lamp of OPERATION
INDICATOR lamp light up ?
<Confirmation of the power to the indoor unit>
Is serial signal error indicated 6 minutes later ?
Turn OFF the power supply.
Check once more if the indoor/outdoor
connecting wire is not mis-wiring.
LED 1
B
Short-circuit outdoor terminal block S2 and
Unit A
status
S3.
Unit C
1
status
Turn ON the power supply.
Does the LED on the outdoor electronic
control P.C. board repeat "3.6-second-OFF
and 0.8-second-ON quick blinking" ?
Turn OFF the power supply.
Remove the short-circuit between
outdoor terminal block S2 and S3.
Turn ON the power supply.
Is there amplitude of 10 to 20 V DC
between outdoor terminal block S2
and S3 ? <Confirmation of serial
signal>
Is there rated voltage between
indoor terminal block S1 and S2 ?
· Reinstall
<Confirmation of power voltage>
either the
unit or the
light away
from each
other.
· Attach a filter
on remote
control Replace the indoor electronic control P.C. board.
receiving
Be sure to release the failure-mode
section of
the indoor recall function after checking.
unit.
Refer to indoor unit service manual.
No
Check the power
supply.
Yes
No
Check the wiring.
Yes
No
Yes
Is there any mis-wiring,
poor contact, or wire
No
disconnection of the
indoor/outdoor
connecting wire ?
Yes
A
1 Mis-wiring may damage indoor electronic control
P.C. board during the operation.
Be sure to confirm the wiring is correct before the
operation starts.
No
(Lighted
or
not lighted)
Yes
No
Yes
Is there any error of the
indoor/outdoor connecting wire,
such as the damage of the wire,
intermediate connection, poor
contact to the terminal block ?
No
Yes
25
Yes
Correct them.
No
Replace the outdoor electronic control
P.C. board.
2
2 Be careful of the residual
voltage of smoothing capacitor.
Replace the
Yes
indoor/outdoor
connecting wire.
No