Mitsubishi MCFH-13NV Service Manual page 36

3. Defrosting
Defrosting of outdoor heat exchanger is controlled by DEICER P.C. board, with detection by the defrost thermistor RT61.
(1) Starting conditions of defrost
When all conditions of a) ~ c) are satisfied, the defrosting operation starts.
a) The compressor cumulative operation time exceeds 40 minutes without the defrosting operation working.
b) The defrost thermistor RT61 reads - 3°C or less.
c) After releasing the high pressure protection 4 minutes and 15 seconds have elapsed.
(2) Releasing conditions of defrost
When the condition d) or e) is satisfied, the defrosting operation stops.
d) The defrost thermistor RT61 reads 3.1°C or more.
e) The defrosting time exceeds 10 minutes.
(3) Defrosting time chart
Defrost thermistor RT61
3.1: or more
-3: or less
Outdoor 52C contactor
(Compressor)
ON
OFF
X62
R.V. coil
ON
OFF
SR61
Outdoor fan
ON
OFF
Defrost
counter
ON
OFF
Indoor fan
ON
Very Low
OFF
Indoor vane
Position 1
Set
Position
NOTE: When the indoor coil thermistor reads above 18°C, indoor fan operates at Very Low for 30 seconds.
When the indoor coil thermistor reads 18°C or less, the indoor fan stops.
15 sec.
30 sec.
Max. 10 min.
NOTE1
30 sec.
(MCFH-24)
(MCFH-13/18)
36
5 sec.