Radiant Panel Temperature Rise, Indoor Electronic Expansion Valve (Motor Operated Valve) Abnormality, Freeze-Up Protection Control (Fvxg Series Only) - Daikin 3MKS50E3V1B Service Manual

Troubleshooting for RA Indoor Unit - FTXG, FTXS, CTXS, FVXG, FVXS, FLXS, FDXS Series
5.4 Radiant Panel Temperature Rise, Indoor Electronic
Expansion Valve (Motor Operated Valve) Abnormality,
Freeze-up Protection Control (FVXG Series Only)
A9
Remote
Controller
Display
Method of Radiant panel temperature rise
During RADIANT operation, high temperature control (e.g., operation halt, indoor electronic
Malfunction
expansion valve closure) is activated according to the temperature detected by the radiant
Detection
panel thermistors.
Indoor electronic expansion valve abnormality
Freeze-up protection control
The temperature detected by the radiant panel thermistors is used to prevent the indoor unit
from freezing during cooling operation.
Malfunction
Radiant panel temperature rise
The radiant panel surface temperature calculated by the radiant panel thermistors is above
Decision
70°C.
Conditions
Indoor electronic expansion valve abnormality
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
278
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.
For multi system
The indoor electronic expansion valve is required to be fully closed in the room where the
system does not run. When the indoor electronic expansion valve is open due to malfunction
and heating or RADIANT operation is conducted in the other room(s), the refrigerant flows
into the radiant panel and the radiant panel temperature rises.
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.
For multi system
While the system does not run and heating or RADIANT operation is conducted in the other
room(s), the temperature detected by the radiant panel thermistor (φ 4) has risen.
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)
SiBE121135
Service Diagnosis