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9
SERVICE FUNCTIONS
MUZ-FE09NA MUZ-FE09NAH MUZ-FE12NA MUZ-FE12NA1 MUZ-FE12NAH MUZ-FE18NA
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
Soldered
(Initial setting)
JS
None
(Cut)
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 temperature.
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
MUZ-FE09NA MUZ-FE09NAH MUZ-FE12NA MUZ-FE12NA1 MUZ-FE12NAH MUZ-FE18NA
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 of 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 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, verify that all connectors and terminals are connected properly.
3) When the electronic control P.C. board seems to be defective, check for disconnection of the copper foil pattern and
burnt or discolored components.
4) Refer to 10-2 and 10-3.
OBH543G
Defrost finish temperature
MUZ-FE09/12NA
MUZ-FE12NA1
MUZ-FE18NA
MUZ-FE09/12NAH
41°F (5°C)
50°F (10°C)
50°F (10°C)
64°F (18°C)
<Incorrect>
Lead wiring
<Correct>
Connector housing
19
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