28
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
MUZ-FH06/09/12NA
MUZ-FH06/09/12NAH
MUZ-FH15/18NA MUZ-FH18NA2
MUZ-FH15/18NAH MUZ-18NAH2
JS
Soldered
(Initial setting)
41°F (5°C)
50°F (10°C)
None
(Cut)
50°F (10°C)
64°F (18°C)
9-2. PRE-HEAT CONTROL SETTING
MUZ-FH06/09/12
When moisture gets into the refrigerant cycle, it may interfere with 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 the discharge temperature ther-
mistor is 68°F (20°C) or below. When the pre-heat control turns ON, the compressor is energized. (About 50 W)
MUZ-FH15/18
Prolonged low load operation, in which the thermostat is OFF for a long time, at low outside temperature [32°F (0°C) or
less] may cause the following troubles. To prevent those troubles, activate the pre-heat control.
1) If moisture gets into the refrigerant cycle and freezes, it may interfer the start-up of the compressor.
2) If liquid refrigerant collects in the compressor, a failure in the compressor may occur.
The pre-heat control turns ON when the compressor temperature is 68°F (20°C) or below. When the pre-heat control
turns ON, the compressor is energized. (About 70 W)
Pre-heat control setting
<JK>
ON: To activate the pre-heat control, cut JK wire of the inverter P.C. board.
OFF: To deactivate the pre-heat control, solder JK wire of the inverter P.C. board.
(Refer to 10-6.1)
Jumper
Pre-heat control setting
MUZ-FH06/09/12NA
MUZ-FH06/09/12NAH
MUZ-FH15/18NA MUZ-FH18NA2
MUZ-FH15/18NAH MUZ-18NAH2
JK
Soldered
Deactivated
(Initial setting)
Deactivated
Cut
Activated
Activated
(Initial setting)
NOTE:
When the inverter P.C. board is replaced, check the jumper wires, and cut/solder them if necessary.
MUZ-FH06NA MUZ-FH06NAH MUZ-FH09NA MUZ-FH09NAH MUZ-FH12NA MUZ-FH12NAH
MUZ-FH15NA MUZ-FH15NAH MUZ-FH18NA MUZ-FH18NAH MUZ-FH18NA2 MUZ-FH18NAH2
OBH684C
