Service Manual

Control Specification SiUS041638E
45 Functions and Control
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 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 temperature +6°C (+10.8°F) < 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 temperature +6°C (+10.8°F) < indoor heat exchanger temperature
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 A seconds. The opening degree of the electronic expansion valve is adjusted by the
following.

Target discharge pipe temperature

Actual discharge pipe temperature

Previous discharge pipe temperature
RK(X)30/36NMVJU
A (seconds) 180
B (seconds) 60
C (seconds) 1020
RK(X)30/36NMVJU
A (seconds) 20
SC
(Subcooling)
SH
(Superheating)
The target discharge pipe
temperature is set as to become
the target SH.
The inclination does not change
depending on the operating condition.
(R23014)