Mitsubishi Electric MSH-18NV Service Manual page 14

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) Under the heat operation, 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
ON
SR61
Outdoor fan
OFF
ON
Defrost
counter
OFF
ON
Indoor fan
VLo
OFF
Horizontal
Indoor vane
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 OB185 REVISED EDITION C when MSH-18NV-
MXZ-32NV-
• Refer to the Service Manual OB227 REVISED EDITION-B when MSH-18NV-
MXZ-32RV-
15 sec.
30 sec.
NOTE1
or MXZ-32NV- as multi system units.
E1 E2
as multi system units.
E1
Max 10 min.
14
30 sec.
5~15 sec.
is connected with
E4
is connected with
E4