Service manual

Troubleshooting SiBE061121_A
68 Service Diagnosis
4.5 Radiant Panel Temperature Rise, Indoor Electronic
Expansion Valve (Motor Operated Valve) Abnormality,
Freeze-up Protection Control
Error Code
A9
Method of Error
Detection
Radiant panel temperature rise
During RADIANT operation, high temperature control (e.g., operation halt, indoor electronic
expansion valve closure) is activated according to the temperature detected by the radiant
panel thermistors.
Indoor electronic expansion valve abnormality
The indoor electronic expansion valve is required to be fully closed during cooling, dry or
heating operation. When the indoor electronic expansion valve is open due to malfunction, the
refrigerant flows into the radiant panel and the radiant panel temperature rises or drops.
The indoor electronic expansion valve is required to be open during RADIANT operation. When
the indoor electronic expansion valve is closed due to malfunction, the refrigerant does not flow
into the radiant panel and the radiant panel temperature does not rise.
Operation stops when any of these cases is detected by the system.
Freeze-up protection control
The temperature detected by the radiant panel thermistors is used to prevent the indoor unit
from freezing during cooling operation.
Error Decision
Conditions
Radiant panel temperature rise
The radiant panel surface temperature calculated by the radiant panel thermistors is above
70°C.
Indoor electronic expansion valve abnormality

During cooling or dry operation, the temperature detected by the radiant panel thermistor
(φ 4) has dropped.

During heating operation, the temperature detected by the radiant panel thermistor (φ 4) has
risen.

During RADIANT operation, the temperature detected by the radiant panel thermistor (φ 4)
does not rise.
Freeze-up protection control
During cooling operation, the operation stops when the temperature detected by the radiant
panel thermistor (φ 4) has dropped.
Supposed
Causes

Clogged air filter of the indoor unit

Dust accumulation on the indoor heat exchanger

Short-circuited air

Defective radiant panel thermistor(s)

Defective indoor heat exchanger thermistor

Defective room temperature thermistor

Defective indoor electronic expansion valve (or coil)