int value = 0;
int ledPin = 5;

void setup() {
  // put your setup code here, to run once:
  Serial.begin(9600);
  pinMode(ledPin, OUTPUT);
}

void loop() {
  // put your main code here, to run repeatedly:
  value = analogRead(A0);
  Serial.print("Temperature sensor value = ");
  Serial.println(value);
  delay(200);

  if (value<300) {
     digitalWrite(ledPin,HIGH);
  } else {
    digitalWrite(ledPin, LOW);
  }
}