Service Functions - Mitsubishi Electric MUZ-GL09NA-U8 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 startup 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 startup 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 JK wire, and cut/solder them if necessary.
OBH733G
Defrost finish 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
(Initial setting)
Activated
MUZ-GL18/24NA
MUZ-GL18/24NAH
50°F (10°C)
64°F (18°C)
MUZ-GL24NA
MUZ-GL24NAH
Deactivated
Activated
(Initial setting)
40