Mitsubishi Electric Mr.Slim PUHZ-SHW80VHA 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
Intake temperature (TH1)
Indoor pipe temperature (TH2)
Indoor 2-phase pipe temperature (TH5)
Set temperature
Pressure saturation temperature (T
Liquid temperature (TH3)
Discharge pipe temperature (TH4)
2-phase pipe temperature (TH6)
Ambient temperature (TH7)
Temperature difference code (intake 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 emegency operation with the values listed above.
2: If one thermistor is set to open/short, the values for each will be different from the list above.
[Example] When pipe temperature thermistor (TH3) has an open or short circuit.
Thermistor
TH3
TH6
TH4
TH5
TH2
T
63HS
OCH526
)
63HS
COOL HEAT
5
45
Tb
Ta
Regard normal figure as effective data.
Tc Td
Regard normal figure as effective data.
50
5
5 45
Tf
Te
Regard normal figure as effective data.
Operation mode
COOL HEAT
27
20.5
5 45
5 50
25
22
50 50
45 5
80
80
50
5
35 7
5 5
30deg
30deg
5deg 5deg
Discharge superheat (SHd)
Cooling = TH4 - T
63HS
Heating = TH4 - T
63HS
Degree of subcooling (SC)
Cooling = T - TH3 = Te - 45
63HS
Heating = T - TH2 = Tf - 45
63HS
53
Remarks
—
—
—
—
( 1)
( 1)
( 1)
( 1)
( 1)
—
( 2)
( 2)
= Tc - Te
= Td - Tf