Control Specification
SiBE041012_B
56
Function and Control
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 outdoor 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:
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 adjustment is made.
1. When the operation mode is cooling
When the following condition is fulfilled, the discharge pipe thermistor disconnection is
ascertained.
Discharge pipe tempe 6°C < outdoor heat exchanger temperature
2. When the operation mode is heating
When the following condition is fulfilled, the discharge pipe thermistor disconnection is
ascertained.
Discharge pipe tempe 6°C < indoor heat exchanger temperature
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 outdoor 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 outdoor 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
outdoor electronic expansion valve is controlled by the followings.
Target discharge pipe temperature
Actual discharge pipe temperature
Previous discharge pipe temperature
25/35 class
50 class
A
(seconds)
10
10
B
(seconds)
120
30
C
(seconds)
810
540
SC
(Subcool)
SH
(Superheat)
The target discharge pipe
temperature is set as to become the
aiming SH.
The inclination does not change
depending on the operating condition.
(R14213)
