Service Functions; Change In Defrost Setting; Pre-Heat Control Setting - Mitsubishi Electric MUZ-GL09NA-U1 Service Manual

9

SERVICE FUNCTIONS

MUZ-GL09NA MUZ-GL09NAH MUY-GL09NA
MUZ-GL12NA MUZ-GL12NAH MUY-GL12NA
MUZ-GL15NA MUZ-GL15NAH MUY-GL15NA
MUZ-GL18NA MUZ-GL18NAH MUY-GL18NA
MUZ-GL24NA MUZ-GL24NAH MUY-GL24NA
9-1. CHANGE IN DEFROST SETTING (MUZ)
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 (MUZ)
MUZ-GL09/12/15/18
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-GL24
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. The pre-heat control prevents those troubles.
1) If moisture gets into the refrigerant cycle and freezes, it may interfere 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
Soldered
JK
Cut
NOTE: When the inverter P.C. board is replaced, check the jumper wires, and cut/solder them if necessary.
OBH733D
Defrost fi nish temperature
MUZ-GL09/12/15NA
MUZ-GL09/12/15NAH
41°F (5°C)
50°F (10°C)
Pre-heat control setting
MUZ-GL09/12/15/18NA
MUZ-GL09/12/15/18NAH
Deactivated
(Factory setting)
Activated
MUZ-GL18/24NA
MUZ-GL18/24NAH
50°F (10°C)
64°F (18°C)
MUZ-GL24NA
MUZ-GL24NAH
Deactivated
Activated
(Factory setting)
40