Service Functions - Mitsubishi Electric MSZ-FD VA Series Service Manual

MUZ-FD50
Sensor
Discharge temperature
thermistor
Indoor coil temperature
thermistor
Defrost thermistor
Fin temperature thermistor
Ambient temperature
thermistor
Outdoor heat exchanger
temperature thermistor
10

SERVICE FUNCTIONS

MUZ-FD25VA MUZ-FD25VAH MUZ-FD35VA MUZ-FD35VAH MUZ-FD50VA
10-1. CHANGE IN DEFROST SETTING
Changing defrost finish temperature
MUZ-FD25/35
<JS> To change the defrost finish temperature, cut/solder the JS wire of the outdoor inverter P.C. board. (Refer to
11-6-1.)
Jumper wire
Soldered
(Initial setting)
JS
None
(Cut)
MUZ-FD50
1. Turn OFF the power supply for the air conditioner before making the setting.
2. Set the 4th Dip Switch of SW1 on the outdoor electronic control P.C. board to
ON to change the defrost finish temperature. (Refer to 11-6-2.)
4th Dip Switch of SW1
OFF
(Initial setting)
ON
10-2. 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 20°C or
below. When pre-heat control is turned ON, compressor is energized. (About 50 W)
MUZ-FD25/35
<JK> To activate the pre-heat control, cut the JK wire of the inverter P.C. board. (Refer to 11-6.1)
NOTE: When the inverter P.C. board is replaced, check the Jumper wires, and cut/solder them if necessary.
MUZ-FD50
[How to activate pre-heat control]
1. Turn OFF the power supply for the air conditioner before making the setting.
2. Set the 2nd Dip Switch of SW1 on the outdoor electronic control P.C. board to
ON to activate pre-heat control function. (Refer to 11-6-2.)
Purpose
Protection
Cooling: Coil frost preven-
tion
Heating: High pressure
protection
Heating: Defrosting
Protection
Cooling: Low ambient tem-
perature operation
Cooling: Low ambient tem-
perature operation
Cooling: High pressure
protection
Defrost fi nish temperature (°C)
5
10
Defrost fi nish temperature (°C)
8.3
12.2
Compressor LEV
○ ○
○
○ ○
○ ○
○
○
○
○ ○
30
Actuator
Outdoor fan
R.V.coil
motor
○ ○
○
○
○
ON
1 2 3 4
ON
1 2 3 4
Indoor fan
motor
○