Mitsubishi Electric PUHZ-P200YHA Service Manual page 53

(5) Operation data during emergency operation
During emergency operation, no communication is performed with the indoor unit, so the data items needed for operation
are set to the following values:
Operation data
Room temperature (TH1)
Indoor pipe temperature (TH2)
Indoor 2-phase pipe temperature (TH5)
Set temperature
Outdoor pipe temperature (TH3)
Outdoor discharge pipe temperature (TH4)
Outdoor 2-phase pipe temperature (TH6)
Outdoor air temperature (TH7)
Temperature difference code (room temperature - set temperature) (Tj)
Discharge superheat (SHd)
Sub-cool (SC)
1: If the thermistor temperature data is normal (not open/short), that data is loaded into the control as valid data.
If the unit enters emergency operation because TH values have become mismatched, setting the thermistors
to open/short corrects the settings.
2: If one thermistor is set to open/short, the values for each will be different.
[Example] When liquid temperature thermistor (TH3) has an open or short circuit.
Thermistor
TH3
TH6
TH4
TH5
TH2
Discharge superheat (SHd)
Cooling = TH4 - TH6 = Tc - Ta
Heating = TH4 - TH5 = Td - 50
Degree of subcooling (SC)
Cooling = TH6- TH3 = Ta -45
Heating = TH5- TH2 = 50 - 45 = 5
OCH424E
COOL HEAT
5
45
Tb
Ta
Regard normal figure as effective data.
Td
Tc
Regard normal figure as effective data.
5 50
45
5
Operation mode
COOL
HEAT
27
20.5
5 45
5 50
25
22
45 5
80 80
50
5
35
7
5 5
30deg 30deg
5deg
5deg
53
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