Malfunctions - Daikin 2MXS40H2V1B Service Manual

SiBE121123_A
4.11.11Target 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 followings.

4.12 Malfunctions

4.12.1 Sensor Malfunction Detection
Sensor malfunction may occur either in the thermistor or current transformer (CT) system.
Relating to Thermistor Malfunction
1. Outdoor heat exchanger thermistor
2. Discharge pipe thermistor
3. Radiation fin thermistor
4. Gas pipe thermistor
5. Outdoor temperature thermistor
6. Liquid pipe thermistor
Relating to CT Malfunction
When the output frequency is more than 52 Hz, abnormal adjustment is carried out.
4.12.2 Detection of Overcurrent and Overload
Outline In order to protect the inverter, an excessive output current is detected and the OL temperature
is observed to protect the compressor.
Detail
Function and Control
SC
(Subcool)
Target discharge pipe temperature
Actual discharge pipe temperature
Previous discharge pipe temperature
If the inverter current exceeds 11.0 ~12.5 A (depending on the model), the system shuts
down the compressor.
If the OL (compressor head) temperature exceeds 120°C, the compressor stops.
The target discharge pipe
temperature is set as to become the aiming SH.
The inclination does not change
depending on the operating condition.
SH
(Superheat)
Control Specification
(R14219)
104