The air conditioner temperature sensor is a sensor that converts the temperature into electricity by using the laws of various physical properties of the substance changing with temperature. These physical properties that show regular changes are mainly physical. The temperature sensor is the core part of the temperature measuring instrument, and there are many varieties. According to the measurement method, it can be divided into two types: contact type and non-contact type. According to the characteristics of sensor materials and electronic components, it is divided into two types: thermal resistance and thermocouple.
Thermal resistance temperature sensors Thermal resistance temperature sensors are divided into metal thermal resistance and semiconductor thermistor. The resistance of most metal thermistors increases as their temperature increases and is said to have a positive temperature coefficient; while the resistance of semiconductor thermistors generally decreases as the temperature increases and is said to have a negative temperature coefficient. Since the resistance values of conductors and semiconductors change with temperature, the corresponding temperature can be measured by measuring their resistance values.
I have specially organized an article on how to judge the quality of the air conditioner temperature sensor. When judging the performance of the air conditioner temperature sensor, the fixed frequency air conditioner should be set to the forced cooling operation state, and the inverter air conditioner should be set to the trial operation state. If the air conditioner can run after this setting, and the working current is basically normal, it can be generally considered that the temperature sensor has a problem. The increase of the resistance value of the air conditioner temperature sensor or the decrease of the resistance value of the compressor temperature sensor will cause the output frequency of the inverter to be low and affect the cooling effect. Of course, there are other methods to judge whether the sensor is good. Let's talk about these methods:
According to the temperature detected by various temperature sensors or artificial simulated temperature to analyze whether the temperature and resistance change curve is normal, in order to judge whether the temperature sensor is bad. The law is: temperature is inversely proportional to resistance.
According to the voltage value input to the single chip microcomputer cPu of various temperature sensors, the current temperature is analyzed to determine whether the temperature sensor is defective. The law is: temperature is proportional to voltage.
In the air-conditioning maintenance work, many air-conditioning maintenance technicians just replace it according to the resistance of the temperature sensor. In fact, there is a major misunderstanding here. In addition to the resistance value, the air conditioner temperature sensor also has a key parameter: the temperature coefficient B value. The temperature coefficient B value refers to the rate of change of the resistance increase percentage with the temperature resistance value when the temperature increases by one degree. Air conditioner manufacturers use 3435, 3450, 3470, 3950, 3960 and so on most. The same resistance value, the temperature coefficient B value is different, the resistance value changes greatly under different temperature conditions. In the air conditioning maintenance, if the resistance value and temperature coefficient B value are selected incorrectly, it may cause the air conditioning unit to fail to operate normally or work abnormally in a certain temperature area. The loss of key protection will eventually damage the key components of the unit and cause significant economic losses to users.
In the repair work of air conditioner, when the air conditioner temperature sensor is damaged, how to detect the original specification parameter resistance value and B value of the air conditioner temperature sensor on site. Is very important. Only if the correct temperature sensor specifications are selected, can the air conditioning unit resume normal operation. It is to avoid that the air conditioning unit has a variety of potential failures due to the wrong temperature sensor selection and cannot be operated stably.
When we repair air conditioners, we often find all kinds of incurable diseases of air conditioner units. For example, the user responds that the cooling of the air conditioning unit is normal and the heating is abnormal. Or often report some temperature-related faults. In fact, most of these faults are related to the wrong temperature sensor selection of the last repairer. If the specifications of the original temperature sensor of the air-conditioning unit manufacturer can be detected on site, we can replace the temperature sensor correctly. Avoid the incurable diseases of air conditioning.