Daikin RXYQ5-48MAY1 Service Manual page 122

Si39-407
6.7.2 Discharge Air Temperature Control
Used to control the EV (electronic expansion valve) opening and thermostat ON/OFF so as to
keep the discharge air temperature at the set temperature.
(1) Cooling operations
Discharge
air
T4
EV
T1: Temperature detected by suction air thermistor Th1
T2: Temperature detected by liquid pipe temp. thermistor Th2
T3: Temperature detected by gas pipe temp. thermistor Th3
T4: Temperature detected by discharge air thermistor Th4
EV: Electronic expansion valve opening
If the discharge temperature
T4 is higher than the discharge
setting temperature Ts
No
Judge if the superheat degree
is not too small when the EV is
opened.
EV=EV+∆EV
Function
T3
T2
Yes
Is EV possible
to open?
Yes
If yes,
EV is opened.
CPU
T1
SH=T3–T2
T4 > Ts?
EV possible to
If yes,
EV is closed.
EV=EV–∆EV
Outline of Control (Indoor Unit)
Refrigerant
Ts
Temp.
Setting
Refrigerant
Calculate superheat degree.
If the discharge temperature T4
is lower than the discharge
setting temperature Ts
No
Is
close?
Judge if the superheat degree
Yes
is not too large when the EV is
closed.
No
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