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3. Defrosting <MUH-07/09/12RV> (Refer to page 118 for MXZ-18/32RV)
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 - 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) RT61 reads 3.1°C or more.
e) The defrosting time exceeds 10 minutes.
NOTE
●
When the indoor coil thermistor RT12 reads above 18°C, indoor fan operates at VLo for 30 seconds.
●
When the indoor coil thermistor RT12 reads 18°C or less, the indoor fan stops.
Defrost thermistor RT61
3.1
:
or more
-3
:
or less
Outdoor 52C
contactor
(Compressor)
X62
(Reversing valve coil)
SR61
Outdoor fan
Defrost
counter
Indoor fan
Indoor
Horizontal vane
ON
OFF
ON
OFF
ON
OFF
ON
OFF
ON
OFF
Horizontal
Set position
Max 10 min.
30 sec.
15 sec.
30 sec.
5 sec.
NOTE
❈
VLo
Operation time chart
Example
