Daikin FDMQ12RVJU, Service Manual

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SiUS091601EA Control Specification
Part 4 Functions and Control 90
5.11.8 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

The time depends on the opening of the electronic expansion valve.
5.12 Malfunctions
5.12.1 Sensor Malfunction Detection
Sensor malfunction can be detected in the following thermistor:
1. Outdoor heat exchanger thermistor
2. Discharge pipe thermistor
3. Radiation fin thermistor
4. Outdoor temperature thermistor
5.12.2 Detection of Overcurrent and Overload
Outline
An excessive output current is detected and the OL temperature is observed to protect the
compressor.
Details
 If the OL (compressor head) temperature exceeds 120 ~ 130°C (248 ~ 266°F) (depending on
the model), the system shuts down the compressor.
 If the inverter current exceeds 12.0 ~ 20.0 A (depending on the model), the system shuts down
the compressor.
The upper limit of the current decreases when the outdoor temperature exceeds a certain level.
09/12/15 class 18/24 class
A (seconds) 10 ~ 30

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)