Troubleshooting - Mitsubishi Electric MSC-GE20VB Service Manual

10

TROUBLESHOOTING

MSC-GE20VB MS-GE50VB
MSC-GE25VB MSH-GE50VB
MSC-GE35VB
10-1. CAUTIONS ON TROUBLESHOOTING
1. Before troubleshooting, check the following:
(1) Check the power supply voltage.
(2) Check the indoor/outdoor connecting wire for mis-wiring.
2. Take care the following during servicing.
(1) Before servicing the air conditioner, be sure to turn OFF the main unit first with the remote controller, and after con-
firming the horizontal vane is closed, turn OFF the breaker and/or disconnect the power plug.
(2) Be sure to turn OFF the power supply before removing the front panel, the cabinet, the top panel, and the electronic
control P.C. board.
(3) When removing the electronic control 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 housing of the connector. DO NOT pull the lead wires.
3. Troubleshooting procedure
(1) First, check if the OPERATION INDICATOR lamp on the indoor unit is flashing ON and OFF to indicate an abnormality.
To make sure, check how many times the OPERATION INDICATOR lamp is flashing ON and OFF before starting serv-
ice 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 10-2. and 10-3.
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.
NOTE1: If the RESET button is not pressed, the remote controller may not operate correctly.
NOTE2 : INFORMATION FOR MULTI SYSTEM AIR CONDITIONER
(OUTDOOR UNIT : MXZ type)
Multi system air conditioner can connect two or more indoor units with one outdoor unit.
According to the capacity, two or more units can operate simultaneously.
•When you try to operate two or more indoor units with one outdoor unit simultaneously, one for the cooling and the
other for heating, the operation mode of the indoor unit that operates earlier is selected. The other indoor units can-
not operate, indicating as shown in the figure below. In this case, please set all the indoor units to the same opera-
tion mode.
•When indoor units start the operation while the defrosting of outdoor unit is being done, it takes a few minutes (max.
10 minutes) to blow out the warm air.
•In the heating operation, though indoor unit that does not operate may get warm or the sound of refrigerant flowing
may be heard, they are not malfunction. The reason is that the refrigerant continuously flows into it.
NOTE3 : This remote controller has a circuit to automatically reset the microcomputer when batteries are replaced.
This function is equipped to prevent the microcomputer from malfunctioning due to the voltage drop caused by the
battery replacement.
NOTE4 : Do not use the leaking batteries.
OBH529A
<Incorrect>
Lead wiring Housing point
Insert the negative pole
of the batteries first.
Check if the polarity of
the batteries is correct.
<Correct>
Press RESET button with a thin instrument, and
then use the remote controller.
Operation Indicator
22
RESET button
Lighted
Flashing