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:
Heat Exchanger (MID) thermistor is open or short is detected always.
Forecast of Cause :
1. Connector failure connection 2. Thermistor failure 3. Controller PCB failure
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
02-11
Trouble shooting 8
INDOOR UNIT Error Method:
Indicate or Display:
Indoor Heat Ex. Thermistor Error
Refer to error code table.
Resistance Value ( )
Temperature (°F)
31.7
95
39.6
86
49.762.9580.3103.3134.2176.0
776859504132
Resistance Value ( )
Temperature (°F)
17.120.925.6
122113104
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)
Small size Wall mount circuit diagram(Connector connection)
If the voltage does not appear, replace Controller PCB and execute the check operation again.
H/E (MID) Thermistor
Room Temp. Thermistor
Room Temp. Thermistor
H/E Thermistor
DC
Cassette circuit diagram (Connector connection)
Wall mount circuit diagram (Direct soldering to PCB)
Duct circuit diagram (Connector connection)
BLACK
BLACK
3
4
CN4
1
2
3
4
1
2
BLACK
BLACK
BLACK
BLACK
BLACK
BLACK
1
2
1
2
CN3
CN1
1
2
3
1
2
3
RED
WHITE
H/E Thermistor
Room Temp. Thermistor
BLACK
BLACK
1
2
1
2
1 1
2 2
CN5
CN8
GRAY
GRAY
1
2
CN7
BLACK
BLACK
1
2
1
2
1 1
2 2
CN5
CN8
GRAY
GRAY
H/E (MID) Thermistor
Room Temp. Thermistor
Floor circuit diagram (Connector connection and Direct soldering to PCB)
BLACK
BLACK
1
2
1
2
1
2
CN3
CN1
GRAY
GRAY
H/E (MID) Thermistor
Room Temp. Thermistor
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