Mitsubishi Electric MSC-C07TV Service Manual page 39

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) RT61 reads - 4.6°C(MUH-C07TV)/ - 2.7°C(MUH-C09/C12TV) 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) RT61 reads 12.8°C(MUH-C07TV)/ 16.3°C(MUH-C09/C12TV) or more.
e) The defrosting time exceeds 10 minutes.
Operation time chart
Example
Defrost thermistor RT61
12.8°C(MUH-C07TV) or more
16.3°C(MUH-C09/C12TV) or more
- 4.6°C(MUH-C07TV) or less
- 2.7°C(MUH-C09/C12TV) or less
ON
Outdoor 52C
contactor
OFF
(Compressor)
ON
X62
(R.V. coil)
OFF
ON
SR61
Outdoor fan
OFF
ON
Defrost
counter
OFF
ON
Indoor fan
Very Low
OFF
Horizontal
Indoor
Horizontal vane
Set position
NOTE When the indoor coil thermistor RT12 reads above 18°C, indoor fan operates at Very Low for 30 seconds.
When the indoor coil thermistor RT12 reads 18°C or less, the indoor fan stops.
15 sec.
30 sec.
Max 10 min.
NOTE
30 sec.
39
5 sec.