#define temp A0
#define fan 2
#define threshold 25

const float BETA = 3950; // should match the Beta Coefficient of the thermistor
float celsius;

int readValue;

void setup()
{
  Serial.begin(9600);
  pinMode(fan, OUTPUT);

} // end of setup()

void loop()
{
  readValue = analogRead(temp);
  celsius = (40./(1023.))*readValue;
  Serial.print("Read value = ");
  Serial.println(readValue);
  Serial.print("Actual value = ");
  Serial.println(celsius);

  if(celsius>threshold)
  {
    digitalWrite(fan, HIGH);
  }
  else
  {
    digitalWrite(fan, LOW);
  }

  delay(500);
} // end program