Warm Air Control; High Pressure Protection Muh-A07/A09/A12Wv - Mitsubishi Electric MSC-A07WV Service Manual

(3) Warm air control.

When the following any condition of 1 (a. ~ c.) and the condition of 2 are satisfied at the same time, warm air control
works.
1 a.) When outdoor unit starts operating inHEAT mode.
b.) When cold air prevention has been released.
c.) When defrosting has been finished
2 When the temperature of indoor coil thermistor RT12 is less than 37°C.
When warm air control works, the fan speed changes as follows to blow out warm air gradually.
Gradation of fan speed in initial
The upper limit of the fan speed in MANUAL is the set speed.
The upper limit of the fan speed in AUTO is the speed decided by indoor fan speed control.(Refer to 11-4.2.(1).)
When the temperature of RT12 has been 37°C or more, or when the set speed has been changed, this control is
released and the fan speed is the set speed.
3. High pressure protection <MUH-A07/A09/A12WV>
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 11-4.4. Defrosting.)
<Time condition>
less than 2 minutes
2 minutes to 4 minutes
more than 4 minutes
High pressure protection
Released
ON
OFF
<Indoor fan speed>
Low
Med.
High
Outdoor fan
OFF
ON
48: 52:
ON
OFF
87
Outdoor fan motor
turn OFF
Outdoor fan motor
turn ON