Mitsubishi Electric MSC-GE-VB Service Manual page 14

Time chart of defrosting in HEAT mode (reverse type)
<Indoor unit>
Set position
Horizontal vane
Indoor fan
Set speed
<Outdoor unit>
Compressor normal
<FD50>
Compressor normal
Outdoor fan
R.V. coil
(21S4)
5. Defrost heater (MUZ-GC·VAH, FD·VAH/VABH, GE·VAH, EF·VEH)
(1) Starting conditions
When all of the following conditions a) ~ d) are satisfied, defrost heater turns ON to prevent ice from foaming on the
base of outdoor unit.
a) HEAT mode is selected.
b) The ambient temperature thermistor reads 5°C or less for 5 minutes continuously. (NOTE 1).
c) The defrost thermistor reads -1°C or less for 5 minutes continuously.
d) Outdoor fan motor is turned ON.
(2) Releasing conditions
When any of the following conditions are satisfied, defrost heater turns OFF.
a) Any other mode than HEAT mode is selected. (NOTE 2).
b) The ambient temperature thermistor reads 8°C or more for 5 minutes continuously. (NOTE 1).
c) The defrost thermistor reads more than 15°C for 5 minutes continuously.
d) Outdoor fan motor is turned OFF.
NOTE 1: Ambient temperature thermistor
5°C 8°C
NOTE 2: During defrosting operation, defrost heater continues to be ON.
Horizontal (Temperature of indoor coil thermistor
Very Low (Temperature of indoor coil thermistor > 18 °C)
30
seconds
Maximum frequency
OFF
40 30
seconds seconds
5 seconds
Reverse defrost frequency
30
seconds
OFF
30 30
seconds seconds
5 seconds
ON
ON (HEAT)
Defrost heater
ON
OFF
Horizontal
39 °C )
OFF
40
seconds seconds
30
seconds seconds
OFF
OFF (COOL)
14
Set position
Set speed
OFF
30
5 seconds
OFF
30
5 seconds
ON
ON (HEAT)