Daikin FTX-N Series Service Manual page 94

Control Specification
5.11.7 Discharge Pipe Thermistor Disconnection Control
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.
Details
Determining thermistor disconnection
When the starting control finishes, the detection timer for disconnection of the discharge pipe
thermistor (A seconds) starts. When the timer is over, the following adjustment is made.
1. When the operation mode is cooling
2. When the operation mode is heating
Other than below
Heating
(When outdoor temperature
is below –15°C (5°F))
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.
89
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
A (seconds)
09/12 class 15 class
720 540
1200 1800
SiUS091601EA
18/24 class
1020
1800
Part 4 Functions and Control