Bluetooth controlled wooden car

#include <Servo.h>
const int motorA1  = 5;  // L298N'in IN3 Girişi
const int motorA2  = 6;  // L298N'in IN1 Girişi
const int motorB1  = 9; // L298N'in IN2 Girişi
const int motorB2  = 10;  // L298N'in IN4 Girişi
Servo servo;

int durum; 
int Hiz=255;
 
void setup() {
    pinMode(motorA1, OUTPUT);
    pinMode(motorA2, OUTPUT);
    pinMode(motorB1, OUTPUT);
    pinMode(motorB2, OUTPUT); 
    servo.attach(7);  
    int aciDegeri=45;
    Serial.begin(9600);
}
 
void loop() {
    if(Serial.available() > 0){     
      durum = Serial.read();   
      servo.write(45);
    }
  
  // Uygulamadan ayarlanabilen 3 hız seviyesi.(Değerler 0-255 arası)
   if (durum == '1'){
      Hiz=50;}
    else if (durum == '2'){
      Hiz=150;}
    else if (durum == '3'){
      Hiz=255;}
         
  /******************** İleri *************************/
    if (durum == 'F') {
      analogWrite(motorA1, Hiz); analogWrite(motorA2, 0);
        analogWrite(motorB1, Hiz);      analogWrite(motorB2, 0); 
    }
  /****************** İleri Sağ *********************/
    else if (durum == 'I') {
      analogWrite(motorA1,Hiz ); analogWrite(motorA2, 0);  
        analogWrite(motorB1,Hiz);    analogWrite(motorB2, 0); 
          servo.write(0);
    }
  /****************** İleri Sol ********************/
    else if (durum == 'G') {
        analogWrite(motorA1, Hiz); analogWrite(motorA2, 0); 
        analogWrite(motorB1, Hiz);      analogWrite(motorB2, 0); 
          servo.write(90);
    }
  /****************** Geri ****************************/
    else if (durum == 'B') {
      analogWrite(motorA1, 0);   analogWrite(motorA2, Hiz); 
        analogWrite(motorB1, 0);   analogWrite(motorB2, Hiz); 
    }
  /******************* Geri Sağ **********************/
    else if (durum == 'J') {
      analogWrite(motorA1, 0);   analogWrite(motorA2, Hiz); 
        analogWrite(motorB1, 0); analogWrite(motorB2, Hiz);
         servo.write(0);
    }
  /******************* Geri Sol *********************/
    else if (durum == 'H') {
      analogWrite(motorA1, 0);   analogWrite(motorA2, Hiz); 
        analogWrite(motorB1, 0);   analogWrite(motorB2, Hiz); 
        servo.write(90);
    }
  /********************** Sağ *************************/
    else if (durum == 'R') {
      analogWrite(motorA1, 0);   analogWrite(motorA2, 0); 
        analogWrite(motorB1, 0); analogWrite(motorB2, 0);
        servo.write(0); 
    }
  /*********************** Sol  *************************/
    else if (durum == 'L') {
      analogWrite(motorA1, 0);   analogWrite(motorA2, 0); 
        analogWrite(motorB1, 0);   analogWrite(motorB2, 0); 
        servo.write(90);    
    }
  /********************* Dur ************************/
    else if (durum == 'S'){
        analogWrite(motorA1, 0);  analogWrite(motorA2, 0); 
        analogWrite(motorB1, 0);  analogWrite(motorB2, 0);
    }  
}