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10-5. If a sensor is defective.
10-5-1. Indoor coil temp. thermistor (TH1) is defective.
• Operation lamp on front side of
indoor unit is flashing on and off. (*)
Alarm Signal (*)
NOTE
Operation lamp on the front side of the indoor unit will flash on and off when the indoor coil thermistor is defective.
At the same time the outdoor unit will stop. Indoor unit will operate only for ventilation.
10-5-2. 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)
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 com-
NOTE
Definition of Open or Short Circuit of Sensor (Thermistor)
Open... A lead wire is broken or disconnected or the circuit inside the temperature sen-
sor 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.
YES
Neither outdoor fan nor compressor runs.
pressor do not stop.
As a result, the room becomes too cold.
• Thermistor (TH1 ) is defective.
(That is, sensor is SHORT.)
• Replace thermistor.
30
YES
Temperature
sensor
Lead
wires
Thermistor Structure
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