Daikin FTXM-V Series Service Manual page 78

Control Specification
3.13.7 Discharge Pipe Thermistor Disconnection Control
Outline
The disconnection of the discharge pipe thermistor is detected by comparing the discharge pipe
temperature with the condensing 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 (Cooling: A seconds, Heating: B seconds) finishes, the detection timer for
disconnection of the discharge pipe thermistor (C seconds) starts. When the timer is over, the
following adjustments are made.
1. When the operation mode is cooling
2. When the operation mode is heating
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.
A (seconds)
B (seconds)
C (seconds)
D
*1 1200 seconds: in heating operation when the outdoor temperature is lower than -10°C (14°F)
*2 1800 seconds: in heating operation when the outdoor temperature is lower than -15°C (5°F)
74
When the following condition is fulfilled, the discharge pipe thermistor disconnection is
ascertained.
(Discharge pipe temperature + D) °C < (outdoor heat exchanger temperature)
When the following condition is fulfilled, the discharge pipe thermistor disconnection is
ascertained.
(Discharge pipe temperature + D) °C < (indoor heat exchanger temperature)
09/12 class
720
(°C)
(°F)
18/24 class
1 30
1 30
*1 *2
1020
6 6
42.8 42.8
SiUS042113E
Part 4 Functions and Control