Mitsubishi Electric Mr.SLIM PUHZ-RP35VHA2 Service Manual page 78

(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 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 ambient 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.
When the unit enters emergency operation and TH values are mismatched, set the thermistors to open/short.
And the unit runs emergency operation with the values listed above.
2: If one thermistor is set to open/short, the values for SHd/SC will be different from the list above.
[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 deg.
COOL
27
5
5
25
45
80
50
35
5
30deg
5deg
HEAT
COOL
5
45
Ta Tb
Regard normal figure as effective data.
Td
Tc
Regard normal figure as effective data.
5 50
45
5
Operation mode
HEAT
20.5
45
50
22
5
80
5
7
5
30deg
5deg
78
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