High - Mitsubishi MSH-18RV Service Manual

5. 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 opera-
tion working.
b) The defrost thermistor RT61 reads - 3°C or less.
c) After releasing the high pressure protection 4 minutes and 15 seconds(MSH-18/24RV)/ 10 seconds(MSH-30RV) 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(MSH-18/24RV)/ 13°C(MSH-30RV) or more.
e) The defrosting time exceeds 10 minutes.
(3) Defrosting time chart
Defrost thermistor RT61
13: or more(MSH-30RV)
3: or more(MSH-18/24RV)
-3: or less
Outdoor 52C
contactor(Compressor)
ON
OFF
X62
(R.V. coil)
ON
OFF
ON
SR61
Outdoor fan
OFF
ON
Defrost
counter
OFF
ON
Indoor fan
Very Low
OFF
Horizontal
Indoor vane
Set position
NOTE1 • 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.
NOTE2 •Refer to the Service Manual OB185 REVISED EDITION C when MSH-18RV-
MXZ-32NV-
•Refer to the Service Manual OB227 REVISED EDITION-B when MSH-18RV-
MXZ-32RV-
•Refer to the Service Manual OB254 when MSH-18RV-
units.
15 sec.
30 sec.
Max 10 min.
NOTE1
or MXZ-32NV- as multi system units.
E1 E2
as multi system units.
E1
30 sec.
(MSH-24/30RV)
(MSH-18RV)
is connected with MXZ-32SV-
E1
41
5 sec.
is connected with
E1
is connected with
E1
as multi system
E1