Daikin CTX Series Service Manual page 39

Control Specification
When starting the compressor, the frequency is initialized according to the ΔD value of the
Initial Frequency
indoor unit.
ΔD signal: Indoor frequency command
The difference between the room thermistor temperature and the target temperature is taken as
the ΔD value and is used for ΔD signal of frequency command.
In Cooling Mode
PI Control 1. P control
2. I control
3. Frequency control when other controls are functioning
4. Upper and lower limit of frequency by PI control
34
Temperature
ΔD signal
difference (°C)
-1.5 0
-1.0 1
-0.5 2
0.0 3
0.5 4
1.0 5
1.5 6
2.0 7
2.5
8
3.0
Temperature
ΔD signal
difference (°F)
-2.7 0
-1.8 1
-0.9 2
0.0 3
0.9 4
1.8 5
2.7 6
3.6 7
4.5
8
5.4
ΔD value is calculated in each sampling time (20 seconds), and the frequency is adjusted
according to its difference from the frequency previously calculated.
If the operating frequency does not change for more than a certain fixed time, the frequency
is adjusted according to ΔD value.
When ΔD is low, the frequency is lowered.
When ΔD is high, the frequency is increased.
 When frequency is dropping:
Frequency control is carried out only when the frequency drops.
 For controlling lower limit:
Frequency control is carried out only when the frequency rises.
The frequency upper and lower limits are set according to the command of the indoor unit.
When the indoor unit quiet operation command comes from the indoor unit, the upper limit
frequency is lower than the usual setting.
In Heating Mode
Temperature
ΔD signal
difference (°C)
-1.5 0
-1.0 1
-0.5 2
0.0 3
0.5 4
1.0 5
1.5 6
2.0 7
2.5 8
3.0
3.5
9
4.0
Temperature
ΔD signal
difference (°F)
-2.7 0
-1.8 1
-0.9 2
0.0 3
0.9 4
1.8 5
2.7 6
3.6 7
4.5 8
5.4
6.3
9
7.2
DAMA-SM-21-003
In Dry Mode
Temperature
ΔD signal
difference (°C)
-1.5 0
-1.0 1
-0.5 2
0.0 3
0.5 4
1.0 5
1.5 6
2.0 7
2.5 8
Temperature
ΔD signal
difference (°F)
-2.7 0
-1.8 1
-0.9 2
0.0 3
0.9 4
1.8 5
2.7 6
3.6 7
4.5 8
Functions and Control