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9
MICROPROCESSOR CONTROL
MUH-A07YV -
E1
MUH-A09YV -
E1
MUH-A12YV -
E1
9-1. HEAT (
) OPERATION
1. High pressure protection
During heating operation, the outdoor fan motor is controlled by the temperature of indoor coil thermistor RT12 for excess
rise protection of compressor discharge pressure.
Outdoor fan OFF: 52:
Outdoor fan ON: 48:
Operation chart
Example
Indoor coil thermistor
RT12 temperature
52˚C
48˚C
Outdoor fan motor
NOTE : During high pressure protection and for 4 min. and 15 sec. after high pressure protection, defrosting of outdoor heat
exchanger is not detected by the defrost thermistor RT61.(Refer to 9-1.2. Defrosting.)
2. 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 - 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 10.1°C or more.
e) The defrosting time exceeds 10 minutes.
High pressure protection
Released
ON
OFF
Outdoor fan
OFF
ON
48: 52:
ON
OFF
20
Outdoor fan motor
turn OFF
Outdoor fan motor
turn ON
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