The program does not execute the command

Good afternoon. I made a program with the DS18B20 temperature sensor to output values ​​in degrees centigrade and degrees farenheit on the lcd display. I also ordered that when it reaches 80 degrees Celsius the LED will light up.
The readings make them perfectly, but the led flashes all the time and is not completely on when it reaches that value.
The verification does not give any error and I do not know what else to do.
This is the programming I wrote:

#include <OneWire.h> //Se importan las librerías
#include <DallasTemperature.h>
#include <LiquidCrystal.h>
#define Pin 3 //Se declara el pin donde se conectará la DATA
int led = 13; // Se declara el pin donde se conectará el led

LiquidCrystal lcd(12, 11, 7, 6, 5, 4);
OneWire ourWire(Pin); //Se establece el pin declarado como bus para la comunicación OneWire
DallasTemperature sensors(&ourWire); //Se instancia la librería DallasTemperature
void setup()
  lcd.begin(16, 2);
  sensors.begin(); //Se inician los sensores
  float val = sensors.getTempCByIndex(0) ; // Almacena valor de temperatura en grados centígrados
void loop()
  sensors.requestTemperatures(); //Prepara el sensor para la lectura
  lcd.print(sensors.getTempCByIndex(0)); //Se lee e imprime la temperatura en grados Celsius
  lcd.print(" Centigrado ");
  lcd.print(sensors.getTempFByIndex(0)); //Se lee e imprime la temperatura en grados Fahrenheit
  lcd.println(" Farenheit ");
  if( sensors.getTempCByIndex(0)>=80.00 );
  if( sensors.getTempCByIndex(0)<80.00);
  delay(5000); //Se provoca un lapso de 5 segundo antes de la próxima lectura

Moderator edit:
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tags added.

  if( sensors.getTempCByIndex(0)>=80.00 );

The semicolon terminates the if statement so what you are seeing is what you told it do do. Remove this semicolon and the one at the end of the other if statement.

Pete P.S. Learn How to post code properly