High Pressure Protection; Discharge Temperature Protection - Mitsubishi Electric MSH-18RV Service Manual

<Time condition>
less than 2 minutes ························Low
2 minutes to 4 minutes···················Med.
4 minutes or more ··························High
The upper limit of the fan speed is the set speed.
If the thermostat turns off, this operation changes to flow soft control.
(4) Flow soft control
After the thermostat turns off, the indoor fan operates at Very Low.
NOTE : When the thermostat turns on, the fan operates at the set speed. Due to the cold air prevention control, the fan
does not start at set speed until the indoor coil thermistor RT12 reads 22°C or more.
2. Outdoor fan speed control <MSH-24/30RV only>
Outdoor fan speed is controlled according to the temperature of ambient temperature thermistor RT63.
Outdoor fan Low operation : Until the outside temperature decreases to 12°C(MSH-24RV)/ 13°C(MSH-30RV).
Outdoor fan High operation :When the outside temperature decreases to 12°C(MSH-24RV)/ 13°C(MSH-30RV) or less.

3. High pressure protection

<MSH-18/24RV>
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.
(MSH-18RV) Outdoor fan OFF : 60°C
Outdoor fan ON : 56°C
(MSH-24RV) Outdoor fan OFF : 52°C
Outdoor fan ON : 48°C
High pressure protection chart
Example
Indoor coil thermistor
RT12 temperature
(MSH-18RV) 60˚C
(MSH-24RV) 52˚C
(MSH-18RV) 56˚C
(MSH-24RV) 48˚C
Outdoor fan motor
NOTE 1 During high pressure protection and for 4 minutes and 15 seconds after high pressure protection, defrosting of
outdoor heat exchanger is not detected by the defrost thermistor RT61.
NOTE 2 When connected to MXZ-32NV-
unit send the data for the temperature to the outdoor unit according to the indoor coil thermistor RT12 temperature.
For the further information, refer to the service manual No.OB185 REVISED EDITION C (Outdoor unit:
MXZ-32NV- or MXZ-32NV-
E1
(Outdoor unit: MXZ-32SV-
<MSH-30RV>
During heating operation, the outdoor fan and the compressor are controlled by the temperature of indoor coil thermistor
RT12 for excess rise protection of compressor discharge pressure.
• Outdoor fan
When the temperature of indoor coil thermistor RT12 goes to 55: or more, the outdoor fan is turned OFF.
When the temperature of indoor coil thermistor RT12 becomes to 52: or less, the outdoor fan is turned ON.
• Compressor
When the temperature of indoor coil thermistor RT12 goes to 75: or more, the compressor is turned OFF.
3 minutes after the compressor is turned OFF and if the temperature of indoor coil thermistor RT12 becomes 75: or less,
the compressor is turned ON.
NOTE : During the high pressure protection and for 10 seconds after high pressure protection, defrosting of outdoor heat
exchanger is not detected by the defrost thermistor RT61.
4. Discharge temperature protection <MSH-30RV only>
Discharge temperature protection is as same as during COOL mode of "I FEEL CONTROL".
<Indoor fan speed>
When the outside temperature goes to 14°C(MSH-24RV)/ 18°C(MSH-30RV) or more.
Until the outside temperature goes to 14°C(MSH-24RV)/ 18°C(MSH-30RV).
High pressure protection
(MSH-18RV)
(MSH-24RV)
ON
,
MXZ-32NV-
E1
), No.OB227 REVISED EDITION-B(Outdoor unit: MXZ-32RV-
E2
) .
E1
Ambient temperature
thermistor RT63 temperature
Released
56:
48:
ON
OFF
,
MXZ-32RV- or MXZ-32SV-
E2 E1
40
Outdoor fan speed
12: 14: (MSH-24RV)
13: 18: (MSH-30RV)
Outdoor fan
OFF
ON
60:
52:
Outdoor fan motor
turn OFF
Outdoor fan motor
turn ON
OFF
outdoor unit, the indoor
E1
E1
High
Low
) or No.OB254