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16
SERVICE FUNCTIONS
9
9-1. CHANGE IN DEFROST SETTING
Changing defrost finish temperature
<JS> To change the defrost finish temperature, cut/solder the JS wire of the outdoor inverter P.C. board.
(Refer to 10-6-1.)
Jumper Defrost fi nish temperature
JS
Soldered
(Initial setting)
41 °F (5 °C)
None
(Cut)
50 °F (10 °C)
MUZ-FD09VA MUZ-FD12VA
9-2. PRE-HEAT CONTROL SETTING
PRE-HEAT CONTROL
When moisture gets into the refrigerant cycle, it may interfere the start-up of the compressor at low outside tempera-
ture. The pre-heat control prevents this interference. The pre-heat control turns ON when outside temperature is 68 °F (20
°C) or below. When pre-heat control is turned ON, compressor is energized. (about 50 W)
<JK> To activate the pre-heat control, cut the JK wire of the inverter P.C. board. (Refer to 10-6.1)
NOTE: When the inverter P.C. board is replaced, check the Jumper wires, and cut/solder them if necessary.
10
TROUBLESHOOTING
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 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, 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 electrical parts, be careful to the residual voltage of smoothing capacitor.
4) When removing the electronic control P.C. board, hold the edge of the board with care NOT to apply stress on the
components.
5) 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) 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) Refer to 10-2. and 10-3.
Lead wiring
Housing point
MUZ-FD09NA MUZ-FD12NA