Mitsubishi Electric MSZ-AY25VGKP-E6 Service Manual page 36

D How to check miswiring and serial signal error
MUZ Type
Check for incorrect indoor-outdoor connecting wiring.
The connection information to the Multi series is stored in
the indoor unit. Refer to "Deleting the memorized abnor-
mal condition" described in 10-2.1 to clear the error his-
tory. When the error history is being cleared, the
connection information also will be initialized. The indoor
unit will be compatible with a low-standby-power model
after initialization.
OK
• Turn OFF inverter-controlled lighting equipment.
• Turn OFF the power supply and then turn ON again.
• Press the emergency operation switch.
Is there rated voltage between outdoor terminal block S1 and S2?
Wait for 2 or more minutes after the main power supply is turned on.
Touch S2 and S3 with multimeter probes and start the emergency operation.
When the emergency operation starts, does the rated voltage occur for
2 seconds between indoor terminal block S2 and S3?
Yes
Does the upper lamp of
OPERATION INDICATOR lamp on
the indoor unit blink continuously
6 minutes after the emergency
operation starts?
Yes
Does the outdoor LED blink 6 times?
Yes
Does DC (6V or more) occur
between indoor terminal block S2
and S3?
Yes
Replace the indoor electronic control
P.C. board. *1
OBH930
Turn the main power supply
OFF.
Is there rated voltage in the power supply?
Yes
Was the indoor unit ever connected to
the Multi (MXZ) series and operated
Yes
(turned on)?
Is serial signal error indicated
6 minutes later?
Yes
Turn the main power supply ON.
Yes
Does the outdoor LED light up?
No
Confirm that the thermostat is OFF
and wiring is not loose.
Replace the outdoor inverter P.C. board. *1
No
Replace the outdoor inverter P.C. board. *1
No
*1.
Electric charge may remain immediately
after the main power supply is turned OFF.
Perform the procedure after 3 minutes.
Check the power supply.
No
No
• Reinstall either the unit or the light
away from each other.
• Attach a filter on remote control
No
receiving section of the indoor unit.
No
No
No
Yes
36
Check for miswiring, broken wires, and loose
wire connection between the main power
supply and outdoor terminal block S1 and
between the main power supply and outdoor
terminal block S2.
Replace the indoor electronic
control P.C. board.