Troubleshooting - Mitsubishi Electric SUZ-M-VA Series Service Manual

11

TROUBLESHOOTING

MFZ-KT25VG MFZ-KT35VG MFZ-KT50VG MFZ-KT60VG
11-1. CAUTIONS ON TROUBLESHOOTING
1. Before troubleshooting, check the following
1) Check the power supply voltage.
2) Check the indoor/outdoor connecting wire for miswiring.
2. Take care of the following during servicing
1) Before servicing the air conditioner, be sure to turn OFF the main unit first with the remote controller, and then after
confirming the horizontal vane is closed, turn OFF the breaker.
2) Be sure to turn OFF the power supply before removing the front panel, the cabinet, the top panel, and the P.C. board.
3) When removing the P.C. board, hold the edge of the board with care NOT to apply stress on the components.
4) When connecting or disconnecting the connectors, hold the connector housing. DO NOT pull the lead wires.
3. Troubleshooting procedure
1) Check if the OPERATION INDICATOR lamp on the indoor unit is blinking ON and OFF to indicate an abnormality.
To make sure, check how many times the OPERATION INDICATOR lamp is blinking ON and OFF before starting
service work.
2) Before servicing, check that the connector and terminal are connected properly.
3) When the electronic control P.C. board seems to be defective, check the copper foil pattern for disconnection and the
components for bursting and discoloration.
4) When troubleshooting, Refer to 11-2, 11-3 and 11-4.
4. How to replace batteries
Weak batteries may cause the remote controller malfunction.
In this case, replace the batteries to operate the remote controller normally.
Remove the front lid and insert batteries.
Then reattach the front lid.
NOTE: 1. If RESET button is not pressed, the remote controller may not operate correctly.
2. This remote controller has a circuit to automatically reset the microprocessor when batteries are replaced.
This function is equipped to prevent the microprocessor from malfunctioning due to the voltage drop caused by
the battery replacement.
3. Do not use the leaking batteries.
5. Description of multi system air conditioner
INDOOR UNIT: MFZ-KT·VG OUTDOOR UNIT: MXZ series
The multi system outdoor unit can be connected to 2 or more indoor units.
• The units do not operate and the operation indicator lamp blinks as shown in the figure below when the total capacity of the
indoor units exceeds the capacity of the outdoor unit. Do not connect the indoor units beyond the outdoor unit capacity.
• When operating the 2 or more indoor units connected to a multi system outdoor unit, set all the indoor units to the
same operation mode. If the COOL and the HEAT modes are selected for those indoor units, the indoor unit which has
started operation first has a priority. The other indoor units set to the different operation mode later do not start opera-
tion and the operation indicator lamp blinks as shown in the figure below.
OPERATION INDICATOR
• When the indoor units start operation while the defrosting of the outdoor unit is being performed, it takes a few minutes (up
to 10 minutes) to blow out warm air.
• In HEAT operation, even though the indoor unit is not running, the room may get warm or the sound of refrigerant flow-
ing may be heard. This is not a malfunction. They happen because the refrigerant is continuously flowing inside the
unit.
OBH843
<Incorrect>
Lead wiring
Connector housing
Insert the negative pole of the
batteries first. Check if the polarity
of the batteries is correct.
Lit (Green)
Blinking
(Green)
Not lit
25
<Correct>
Press RESET button with a thin instrument, and
then use the remote controller.
RESET button