Mitsubishi Electric CITY MULTI PUHY-80TMU-A Service Handbook page 32

5) Change in number of operating indoor units during defrosting operations
• In case number of operating indoor units changes during defrosting operations, the defrosting operations continue,
and control of unit number change is performed after the defrosting operations are finished.
• Even in case all indoor units stop or thermostat is turned off during defrosting operations, the defrosting operations
do not stop until expected defrosting activities are completed.
(8) Control of liquid level detecting heater
Detect refrigerant liquid level in accumulator, and heat refrigerant with liquid level heater for judging refrigerant
amount. 6 steps of duty control is applied to liquid level heater depending on frequency and outdoor air temperature,
1minute after starting compressor.
(9) Judgement of refrigerant amount
Cooling
Compressor
Frequency
20~45Hz
TdSH
50<TdSH
45<TdSH < 50
- -
40<TdSH < 45
- -
20<TdSH < 40
- -
TdSH < 20
- -
Heating
TH5
TH5 < 5°C
TdSH
90<TdSH
70<TdSH < 90
- -
50<TdSH < 70
- -
20<TdSH < 50
- -
TdSH < 20
- -
TdSH=Discharge Super Heat.
=Td-Tsg (low pressure saturation temperature)
46~70Hz
AL=0 AL=0
AL=1 AL=0
AL=1 AL=1
AL=1 AL=1
AL=2 AL=2
5°C < TH5 < 15°C
- -
AL=0
AL=0
AL=1 AL=0
AL=1
AL=1
AL=1
AL=1
AL=2 AL=2
71Hz~Fmax
AL=0
AL=0
AL=0
AL=1
AL=2
15°C < TH5
- -
AL=0
AL=0
AL=0
AL=1
AL=2
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