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50PCS
Cable Length about 360mm
Generally, 5K-10K is more commonly used for hanging up Most cabinet machines use 10K to 20K. You need to measure the resistance value yourself with a multimeter
A general ambient temperature sensor is a small black object located near the fins on the wall side of the outdoor unit. The tube temperature sensing head is inserted into the wall of the coil inside the outdoor unit.
The copper head is used to detect copper pipes and has fast temperature conduction; Rubber heads are generally used to detect environmental temperature, are corrosion-resistant, and have high reliability
How to determine the resistance of the air conditioning temperature sensor
The air conditioning circuit designer takes the room temperature of 25 degrees as the reference, that is, at 25%, RTl=R1, RT2=R2, and the voltage at points A and B is 2.5V. Some circuits are equipped with R3 and R4, mainly for buffering purposes. When the ambient temperature increases, the RTI resistance decreases and the voltage at point A increases. The comparator outputs a differential pressure, which is processed internally by the CPU to control the operation status of the internal and external units.
The sampling voltage of the temperature sensor connected to the external control board of large air conditioners and variable frequency air conditioners is not 2.5V, but 1/4 of the power supply voltage, which is 1.25V. In fact, there is a very simple method to determine the resistance value of the thermistor. Choose a 50k potentiometer and a universal plug for the thermistor. For convenience, connect them with a long wire, unplug the suspected thermistor, plug in the universal plug, power on the air conditioner, use a multimeter 5V to test the voltage of the two terminals of the potentiometer, slowly rotate the potentiometer handle, and when the voltage is 2.5V, stop rotating. At this time, the resistance value of the potentiometer is the resistance value of the thermistor. For example, if the resistance value is 8k and the ambient temperature is around 30 ℃, then the resistance value of the temperature sensor is 10k.
How to judge the quality of the air conditioning temperature sensor
The following phenomena may occur when the air conditioning temperature sensor is broken, which can be used to determine the quality of the air conditioning temperature sensor:
1. The resistance of the indoor ambient temperature sensor increases, causing the air conditioner to start frequently.
2. The resistance of the indoor pipe temperature sensor decreases, causing the whole machine to be protected shortly after startup.
3. Changes in indoor ambient temperature and pipe temperature sensing performance can cause air conditioning to malfunction.
4. The indoor pipe temperature change value is 0 Ω, causing the whole machine to have no response when remotely turned on.
The air conditioning temperature sensor is broken. Solution:
Temperature sensor faults account for a large proportion of air conditioning failures. To accurately determine, one must first understand its function. The air conditioning control section is equipped with three temperature sensors:
1. Room temperature sensor: mainly detects the indoor temperature. When the indoor temperature reaches the set requirements, it controls the operation of the internal and external units. When cooling, the external unit stops and the internal unit continues to operate. When heating, the internal unit blows waste heat and stops.
2. Indoor tube temperature sensor: mainly detects the temperature of the coil of the indoor evaporator, and plays a role in preventing cold air, overheating protection, and automatic temperature control during heating.
3. Outdoor defrosting temperature sensor: mainly detects the temperature of the outdoor condenser coil. When the temperature of the outdoor coil is below -6 degrees Celsius for 2 consecutive minutes, the indoor unit will switch to defrosting state. When the resistance value of the outdoor coil sensor is too high, the indoor unit cannot work normally.
Analysis of the reasons for the inconsistency between the displayed temperature of the air conditioner and the actual perceived temperature:
1. Incorrect remote control settings;
2. The filter screen was not cleaned in a timely manner;
3. There are items in the air conditioning inlet and outlet that affect the heating effect, and the room has a heat source or a large number of people inside, resulting in poor cooling effect;
4. Poor room insulation effect;
5. Low indoor power supply voltage leads to low efficiency of air conditioning operation;
6. Poor performance due to excessively high or low ambient temperature.
During the maintenance process of air conditioning, the failure rate of temperature sensors (thermistors) is relatively high. Once open circuits, short circuits, or poor characteristic curves occur, the air conditioning will display abnormal codes and cannot function properly. Due to the lack of parameters and resistance values indicated on the temperature sensor, it is often difficult to determine during maintenance. Even for the same brand but different models, their resistance values may not be the same.
Temperature sensor, which reduces resistance when the temperature rises; When the temperature decreases, the resistance increases. The negative sampling voltage of the CPU comparator is 1/2 of the CPU power supply voltage, which is 2.5V. And the pull-up resistors at the positive terminals of the RTl and RT2 operational amplifiers comparator in the peripheral circuit, R1 and R2 are the down bias resistors.
