9-5. If a sensor is defective.
A. Open
When thermistor opens, the air conditioner will be in the following conditions as the controller tries to detect extremely low indoor coil temperature.
In Cooling mode: Function of freeze prevention continues to work. That is, the controller turns both compressor and outdoor fan motor periodically ON and OFF for several minutes. (Refer to
B. Short
When thermistor is short, the air conditioner will be in the following conditions as the controller tries to detect extremely high indoor coil temperature.
In Cooling mode: Function of freeze prevention will not work even when the frost builds up on indoor heat exchanger coil
9-5-2. Room temp. thermistor (TH2) 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.
In Cooling mode: The air conditioner soon stops and will not start again. (Thermo.OFF) Neither outdoor fan nor compressor runs.
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.
In Cooling mode: The air conditioner continues to operate (Thermo.ON). Both the outdoor fan and compressor do not stop. As a result, the room becomes too cold.
Temperature sensor
Lead wires
NOTE
Definition of Open or Short Circuit of Sensor (Thermistor)
Thermistor Structure
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.
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