If A Sensor Is Defective - Sanyo STW-2 Series Technical & Service Manual

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)
b) In Heating mode: The air conditioner continues to operate. (Thermo.ON)
(Heat pump)
B. Short
When thermistor is shorted, 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)
b) In Heating mode: The air conditioner soon stops and will not start again. (Thermo.OFF)
(Heat pump)
NOTE
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.
Compressor does not run.
Electric heater does not stop.
As a result, the room becomes too warm.
Compressor does not stop.
As a result, the room becomes too cold.
Neither compressor nor electric heater runs.
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Temperature
sensor
Lead
wires
Thermistor Structure