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Functions of Air Conditioner Temperature Sensor

Functions of Air Conditioner Temperature Sensor

Ⅰ. Types of air conditioner temperature sensors


1. Room temperature sensor


The room temperature sensor is installed in the air inlet of the indoor evaporator of the air conditioner. It is supported by plastic parts, and can be used to detect whether the indoor temperature reaches the set value. The functions are as follows.


① The air conditioner temperature sensor is used to automatically control the indoor temperature during heating or cooling.


② It is used to control the auxiliary electric heater when heating.


2. Indoor evaporator pipeline temperature sensor


The indoor evaporator pipeline temperature sensor is installed in the indoor evaporator pipeline. It is wrapped in metal tubes. The air conditioner temperature sensor is directly in contact with the pipeline, so the temperature measured is close to the evaporation degree of the refrigeration system. The functions are as follows.


① Process control during summer cooling. (To prevent insufficient refrigerant in the system or frost in indoor evaporator).


② The HVAC temp sensor is used to prevent cooling when heating in winter.


③ It is used to control the speed of indoor fan motors.


④ Cooperate with SCM to realize fault self-diagnosis.


⑤ Assist outdoor unit in defrosting when heating.


3. Outdoor ambient temperature sensor


The outdoor ambient temperature sensor is mounted on the radiator of the outdoor unit. It is supported by plastic parts. The air conditioner temperature sensor is used to detect outdoor ambient temperature. The main functions are as follows.


① It is used to control the speed of outdoor fan motor during cooling or heating.


② Automatically protect the control system when the outdoor temperature is too low or too high.


4. Air conditioner temperature sensor for outdoor condenser pipe


The air conditioner temperature sensor for outdoor condenser pipe is mounted on the radiator of the outdoor unit and is packed with metal tubes. It is used to detect outdoor pipe temperature. The main functions are as follows.


① It is used for outdoor unit defrosting when heating.


② Protect against overheating or freezing when refrigerating or heating.


5. Outdoor unit compressor exhaust temperature sensor


Outdoor unit compressor exhaust temperature sensor is installed on the exhaust pipe of the outdoor unit compressor and is packed with metal tubes. The main functions are as follows.


① When the compressor exhaust pipe temperature is too high, the control system automatically protects it.


② It is used to control the opening degree of electronic expansion valve and the rise and fall of compressor operation frequency in frequency conversion air conditioner.


Ⅱ. Fault detection of air conditioner temperature sensor


1. In-circuit detection of temperature sensor


Take out the circuit board in the indoor machine from the fixed module, connect the components, and connect to the power supply. Detect the air conditioner temperature sensor to check whether the voltage sent to the microprocessor is normal, and the condition of the air conditioner temperature sensor can be judged immediately. The personal safety should be paid attention to when conducting in-circuit detection.


The detection of the temperature sensor with a multimeter should be carried out at the solder joint on the reverse side of the computer board. Ground the black stylus of the multimeter, and connect the red stylus to the solder joint of the temperature sensor. Set the voltage of the multimeter to 20 V.


Under normal circumstances, the voltage sent by the indoor HVAC temp sensor to the microprocessor should be about 2 V. If the sensor is damaged, the measured voltage is 0 V.


The voltage sent by the evaporator pipeline temperature sensor to the microprocessor should be about 3 V. If the sensor is damaged, the measured voltage is 0 V. If the sensor voltage is 0 V, it means that the external sensor is damaged and should be replaced.


2. Open circuit detection of temperature sensor


In addition to the in-circuit detection of the temperature sensor, the open circuit detection should be carried out in the air conditioning temperature sensor. Their resistance under different temperature conditions should be measured. In this way, we can judge whether the temperature sensor is in a good condition.


The detection method is the same as the in-circuit detection. It is measured by a multimeter. If the resistance of the temperature sensor is always very large and tends to infinity, it indicates that the temperature sensor is faulty.


If the open circuit detection of the air conditioner temperature sensor is normal, but the pin voltage is too high or too low in the in-circuit detection, it is necessary to further detect the circuit part to troubleshoot the fault.