temperature based fan speed controlling using arduino.. lm35 and arduino

#include <LiquidCrystal.h>
LiquidCrystal lcd(12, 11, 5, 4, 3, 2);
int enable2 = 6;

int in3 = 10;

int in4 = 9;
const int sensor=A1; // Assigning analog pin A1 to variable ‘sensor’
float tempc; //variable to store temperature in degree Celsius
float tempf; //variable to store temperature in Fahreinheit
float vout; //temporary variable to hold sensor reading
void setup()
{
pinMode(enable2, OUTPUT);
pinMode(in3, OUTPUT);
pinMode(in4, OUTPUT);
pinMode(sensor,INPUT); // Configuring pin A1 as input
Serial.begin(9600);
lcd.begin(16,2);
lcd.print("…");
delay(2000);
lcd.clear();
lcd.print(“SYSTEM READY”);
delay(3000);
lcd.clear();
}
void loop()
{
lcd.clear();
vout=analogRead(sensor);
vout=(vout500)/1023;
tempc=vout; // Storing value in Degree Celsius
tempf=(vout
1.8)+32; // Converting to Fahrenheit
Serial.print(“in DegreeC=”);
Serial.print("\t");
Serial.print(tempc);
Serial.println();
Serial.print(“in Fahrenheit=”);
Serial.print("\t");
Serial.print(tempf);
Serial.println();
lcd.setCursor(0,0);
lcd.print(“Temp:”);
lcd.print(tempc);
lcd.print(“C”);
if(tempc<10)
{
analogWrite(enable2, 200); // Any value between 0 and 255

digitalWrite(in3, LOW);

digitalWrite(in4, LOW);

}
if(tempc<20&&tempc>10)
{
analogWrite(enable2, 100); // Any value between 0 and 255

digitalWrite(in3,HIGH);

digitalWrite(in4, LOW);

}
if(tempc>20&&tempc<25)
{
analogWrite(enable2, 150); // Any value between 0 and 255

digitalWrite(in3,HIGH);

digitalWrite(in4, LOW);

}
if(tempc>25)
{
analogWrite(enable2, 200); // Any value between 0 and 255

digitalWrite(in3,HIGH);

digitalWrite(in4, LOW);

}
delay(500);
}

...and?

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