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7-5. If a sensor is defective. (Only for heat pump model)
7-5-1. Room temp. thermistor (RTH) is defective.
A. Open
When thermistor opens, the air conditioner will be in the following conditions
as the controller tries to detect extremely low room temperature.
a) In Cooling mode: The air conditioner soon stops and will not start again. (Thermo.OFF)
Compressor does not run.
b) In Heating mode: The air conditioner continues to operate. (Thermo.ON)
(Heat pump) Electric heater does not stop.
As a result, the room becomes too warm.
B. Short
When thermistor is short, the air conditioner will be in the following conditions
as the controller tries to detect extremely high room temperature.
a) In Cooling mode: The air conditioner continues to operate. (Thermo.ON)
Compressor does not stop.
As a result, the room becomes too cold.
b) In Heating mode: The air conditioner soon stops and will not start again. (Thermo.OFF)
(Heat pump) Neither compressor nor electric heater runs.
Definition of Open or Short Circuit of Sensor (Thermistor)
Open...A lead wire is broken or disconnected or the circuit inside the temperature sensor is open .
Short... The protective cover of a lead wire has been damaged, and the exposed wire is touching another metal
part, or both lead wires have become exposed and are touching each other. Alternatively, the circuit inside
the temperature sensor is closed.
NOTE
34
Temperature
sensor
Lead
wires
Thermistor Structure