Thermistor Characteristics (Rough value)
If Thermistor is either open or shorted, replace it and reset the power.
Detective Actuators:
Indoor Unit Controller PCB
Heat Exchanger (MID) Thermistor
Detective details:
Indoor unit thermistor is open or short is detected always.
Forecast of Cause :
1. Connector failure connection 2. Thermistor failure 3. Controller PCB failuer
Check Point 1 : Check connection of Connector
Check if connector is loose or removed
Check erroneous connection
Check if thermistor cable is open
>>Reset Power when reinstalling due to removed connector or incorrect wiring.
OK
Check Point 2 : Remove connector and check Thermistor resistance value
OK
Check Point 3 : Check voltage of Controller PCB (DC5.0V)
Make sure circuit diagram of each indoor unit and check terminal voltage at Thermistor (DC5.0V)
If the voltage does not appear, replace Controller PCB and execute the check operation again.
DC
BLACK
BLACK
BLACK
BLACK
1
2
1
2
CN3
CN1
1
2
3
1
2
3
RED
WHITE
H/E Thermistor
Room Temp. Thermistor
02-09
Trouble shooting 7
INDOOR UNIT Error Method:
Indicate or Display:
Indoor Heat Ex. Thermistor Error
Refer to error code table.
31.7
95
39.6
86
49.7
62.9
80.3
103
134
176
77
68
59
50
41
32
Temperature (°F )
17.1
20.8
25.6
Resistance value (k )
122
113
104
Temperature (°F )
Temperature (°C )
Temperature (°C )
0
40
45
50
5
10
15
20
25
30
35
Resistance value (k )