Troubleshooting; Cautions On Troubleshooting - Mitsubishi Electric MSH09TW Service Manual

12

TROUBLESHOOTING

MSH09TW MSH09TW -
MSH12TN MSH12TN -
MSH15TN MSH15TN -
MSH17TN MSH17TN -

12-1. 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, first be sure to turn off the remote controller to stop the unit, and then 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 abnormality indication is flashing on and off before starting service work.
2) Before servicing check that the connector and terminal are connected properly.
3) If the electronic control P.C. board is supposed to be defective, check the copper foil pattern for disconnection and
the components for bursting and discoloration.
4) When troubleshooting, refer to the flow chart on page 76, 77 and the check table on page 78, 79, 80.
4. How to replace batteries
Weak batteries may cause the remote controller malfunction.
In this case, the remote controller can be repaired only by the battery replacement. To operate the remote controller nor-
mally, replace the batteries in the following order.
This remote controller has the RESET button. After refilling new batteries, press the RESET button with tip end of ball
point pen or the like, and then use the remote controller.
1 Remove the front lid and replace batteries.
Then re-attach the front lid.
NOTE : If the RESET button is not pressed, the remote controller may not operate correctly.
MUH09TW MUH09TW -
U1
MUH12TN MUH12TN -
U1
MUH15TN MUH15TN -
U1
MUH17TN MUH17TN -
U1
Lead wiring
Insert the negative pole
of the batteries first.
Check if the polarity of
the batteries are correct.
MUH12TN -
U1
MUH15TN -
U1
U1
U1
Housing point
2 Press the RESET button.
RESET button
75
MXZ30TN
U2
MXZ30TN2
U2