NTC like KY-013 but with 100K

Hello everyone,
I am trying to make use of my Sensor which looks like this KY-013:
As mentioned in other threads, the pins were wrong labeled. Using my multimeter I figured that
Left (labeled S) is the Signal (Voltage divider)
Middle is GND
Right (labeled -) is Vcc

The example code for the KY-013 (wich can be found on several websites) throws out negative Values (in the right range) and as soon as I heat the NTC up the displayed temperature decreases and vice versa:

#include <math.h>
 
int sensorPin = A5; 

double Thermistor(double resistance) {
  double Temp;
  Temp = log(resistance);
  Temp = 1 / (0.001129148 + (0.000234125 * Temp) + (0.0000000876741 * Temp * Temp * Temp));
  Temp = Temp - 273.15; 
  return Temp;
}
 
void setup() {
 Serial.begin(9600);
}
 
void loop() {
 int readVal = analogRead(sensorPin);
 double  resistance = ((10240000/readVal) - 10000);
 double temp =  Thermistor(resistance);

 Serial.print(temp);  // display tempature
 Serial.print(" C   ");
 Serial.print(readVal);  // display 
 Serial.print(" ByteVal   ");
 Serial.print(resistance);  // display 
 Serial.println(" Ohm   ");
 
 delay(100);
}

I measured the NTC and it seems to be a 100k Ohm NTC and not a 10k Ohm NTC which is normally used for the KY-013 (at least from my point of view).

Here is an image of the transient behavior when I touch the NTC in a normal room (approx. 20-25 °C room temperature):

IMO the constants of the Steinhart-Hart equation seems to be wrong. I don’t have another thermometer to figure them out by my self. Has anyone already did this or more precise Values?
Thank you in advance.

Codebot:
as soon as I heat the NTC up the displayed temperature decreases and vice versa:

Then swap sensor VCC and ground.

That board is just a thermistor and a 10k resistor (marked 103) voltage divider, with the center tap going to the analogue pin.
Temp goes one way if the thermistor is connected to ground and the resistor to VCC.
Temp goes the other way if thermistor is connected to VCC and resistor is connected to ground.
Leo..

Swapping leads to temps above 100°C..
There is no need for swapping as you can see the measauered resistance is correct. It rises/drops in the wrong way due to wrong coefficients. I divided to the resistance value by 10 (as the coefficients are for a 10k ntc and I am having a 100k NTC). No it works pretty good but I doubt it to be precise.

The A/D should return the same digital values with a 100k thermistor/100k resistor as with a 10k/10k combo. Check if the pull up resistor has the same value as the thermistor.
Thermistor code uses the crooked*crooked=straight principle.
I think just ok for a small temp span, or for crude things like thermostats.
A digital DS18B20 could be better/easier.
Leo..

Sorry, I forgot to mention its a 100k NTC / 10 K Resistor Combo (yeah...). I will buy others as its not worth spending to much time for a super cheap sensor with a missing data sheet. Still thanks for helping.

Try with a 90k (2*180k parallel) resistor in series with the 10k pull up resistor.
Leo…

IMO the constants of the Steinhart-Hart equation seems to be wrong.

There are various ways to determine the Steinhart-Hart coefficients for your thermistor.

Here is an on line calculator.