Daikin FTXS30LVJU Service Manual page 63

Control Specification
3.11.7 Control for Disconnection of the Discharge Pipe Thermistor
Outline The disconnection of the discharge pipe thermistor is detected by comparing the discharge pipe
temperature with the condensation temperature. If the discharge pipe thermistor is disconnected,
the electronic expansion valve opens according to the outdoor temperature and the operation
frequency, operates for a specified time, and then stops.
After 3 minutes, the operation restarts and checks if the discharge pipe thermistor is disconnected.
If the discharge pipe thermistor is disconnected, the system stops after operating for a specified
time.
If the disconnection is detected repeatedly, the system is shut down. When the compressor runs for
60 minutes without any error, the error counter is reset.
Detail
When the starting control (cooling:
disconnection of the discharge pipe thermistor (
following adjustment is made.
1. When the operation mode is cooling
2. When the operation mode is heating
A (seconds)
B (seconds)
C (seconds)
Adjustment when the thermistor is disconnected
When the disconnection is ascertained, the compressor continues operation for 9 minutes and then
stops.
If the compressor stops repeatedly, the system is shut down.
3.11.8 Target Discharge Pipe Temperature Control
The target discharge pipe temperature is obtained from the indoor and outdoor heat exchanger
temperature, and the electronic expansion valve opening is adjusted so that the actual discharge
pipe temperature becomes close to the target discharge pipe temperature. (Indirect SH
(superheating) control using the discharge pipe temperature)
The electronic expansion valve opening and the target discharge pipe temperature are adjusted
every 20 seconds. The target discharge pipe temperature is controlled by indoor heat exchanger
temperature and outdoor heat exchanger temperature. The opening degree of the electronic
expansion valve is controlled by the followings.
 Target discharge pipe temperature
 Actual discharge pipe temperature
 Previous discharge pipe temperature
53
When the following condition is fulfilled, the discharge pipe thermistor disconnection is
ascertained.
Discharge pipe temperature + 6°C (+ 10.8°F) < outdoor heat exchanger temperature
When the following condition is fulfilled, the discharge pipe thermistor disconnection is
ascertained.
Discharge pipe temperature + 6°C (+ 10.8°F) < indoor heat exchanger temperature
09/12 class
10
120
810
SC
(Subcool)
A seconds, heating: B seconds) finishes, the detection timer for
C seconds) starts. When the timer is over, the
15/18/24 class
10
30
540
The target discharge pipe
temperature is set as to become the
aiming SH.
The inclination does not change
depending on the operating condition.
SH
(Superheat)
SiUS091133
30/36 class
30
30
540
(R14213)
Function and Control