Mitsubishi Electric MCFH-13NV-E3 Service Manual page 20

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°C or more.
e) The defrosting time exceeds 10 minutes.
(3) Defrosting time chart
Defrost thermistor RT61
3: or more
-3: or less
Outdoor 52C contactor
(Compressor)
ON
OFF
X62
(Reversing valve.coil)
ON
OFF
SR61
Outdoor fan
ON
OFF
Defrost
counter
ON
OFF
Indoor fan
ON
VLo
OFF
Indoor vane
Position 1
Set
Position
NOTE1 : When the indoor coil thermistor reads above 18°C, indoor fan operates at VLo for 30 seconds.
When the indoor coil thermistor reads 18°C or less, the indoor fan stops.
NOTE2 : Refer to the Service Manual OB227 REVISED EDITION-B when MCFH-13NV-
as multi system units.
15 sec.
30 sec.
Max 10 min.
NOTE1
30 sec.
20
5 sec.
is connected with MXZ-32RV-
E3 E1