Arduino Temperature sensor with a LED I want to program a temperature sensor with a LED using Arduino. 
the goal is to make a sensor, when the temperature is over than Temperature max, the LED turns off and when the temperature is small than temperature max we turn on the LED.

my problem is when I programed the void setup() as followed, the LED doesn't work, and when I comment Serial.begin (9600) the LED work but I cannot diplay the value of the temperature. 

void setup() {
   Serial.begin(9600);
   pinMode(tempPin, INPUT);
   pinMode(led, OUTPUT);
}


here you find my complet code:

    int tempPin = A0;   // the output pin of LM35
float Max_temp = 24.0;
int led = 1;

float  temp, cel;
void setup() {
   Serial.begin(9600);
   pinMode(tempPin, INPUT);
   pinMode(led, OUTPUT);
}
void loop() { 
      cel = readTemp(); 
  if(cel&lt; Max_temp) {        // if temp is higher than tempMax
      digitalWrite(led, HIGH);  // turn on led
      delay(300);
     } 
     else {                    // else turn of led
       digitalWrite(led, LOW);  // turn on led
      delay(100);
  }
   Serial.print("TEMP: ");
   Serial.print(cel);      // display the temperature
   Serial.print("C ");
   Serial.println();
   delay(300);  
}

float readTemp() {  // get the temperature and convert it to celsius
  temp = analogRead(tempPin);
  return temp * 0.48828125;
}


thank you very much in advance
int led = 1;


You do know that pins 0 and 1 are the serial port don't you?

Take your pick.... Either use pin 1 for the LED OR use pin 1 for the serial connection.  You can't do both!

As it says in the manual:


  In addition, some pins have specialized functions:
  
  
  Serial: 0 (RX) and 1 (TX). Used to receive (RX) and transmit (TX) TTL serial data. These pins are connected to the corresponding pins of the ATmega8U2 USB-to-TTL Serial chip.