Service manual

SiUS28-902_a Troubleshooting by Indication on the Remote Controller
Troubleshooting 96
3.9 “C4” Indoor Unit: Malfunction of Thermistor (R2T) for
Heat Exchanger
Remote
Controller
Display
C4
Applicable
Models
All indoor unit models
Method of
Malfunction
Detection
Malfunction detection is carried out by temperature detected by heat exchanger thermistor.
Malfunction
Decision
Conditions
When the heat exchanger thermistor becomes disconnected or shorted while the unit is running.
Supposed
Causes
 Defect of thermistor (R2T) for liquid pipe
 Defect of indoor unit P.C.B.
Troubleshooting
∗ Refer to thermistor resistance / temperature characteristics table on P.166.
Caution
Be sure to turn off the power switch before connecting or disconnecting
the connector, or parts could be damaged.
Replace the indoor unit P.C.B.
Connect the thermistor and turn
on again.
NO
NO
Replace the thermistor (R2T).
YES
YES
Connector
is connected to X12A
of the indoor unit
P. C . B .
Resistance
is normal when
measured after
disconnecting the thermistor
(R2T) from the indoor
unit P.C.B.
(3.5kΩ ~
360kΩ)
KΩ