Mitsubishi Electric PUHZ-P100VHA.UK Service Manual page 54

(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
Intake temperature (TH1)
Indoor liquid pipe temperature (TH2)
Indoor 2-phase pipe temperature (TH5)
Set temperature
Outdoor fluid pipe temperature (TH3)
Outdoor 2-phase pipe temperature (TH6)
Outdoor air temperature (TH7)
Temperature difference code (intake temperature - set temperature) (∆Tj)
Discharge super heat (SHd)
Sub-cool (SC)
w1: 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.
w2: 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
TH5
TH2
Degree of subcooling (SC)
Cooling = TH6- TH3 = Ta -45
Heating = TH5- TH2 = 50 - 45 = 5 deg.
COOL
27:
5:
5:
25:
45:
50:
35:
30deg
5deg
HEAT
COOL
45: 5:
Tb
Ta
Regard normal figure as effective data.
5: 50:
45:
5:
Operation mode
HEAT
20.5:
45:
50:
22:
5:
5:
5:
5 5
30deg
5deg
54
Remarks
(w1)
(w1)
(w1)
(w2)
(w2)