What is wrong with my if else statements?

This code is functioning almost perfectly but it seems to be ignoring my if else statements. The goal of this program is to only convert temperatures between -100 and 100 but for some reason my code is still converting any number that is entered. It is frustrating because I have tried several different approaches but the program never goes to the else statement and always runs the if statement even if say I entered 10000. Thank you any advice would be appreciated

double converter()
{
  float C, F, S; 
  int input;
  printf ("Please enter a temperature in Fahrenheit:");

  scanf ("%f", &F); 

  if (F > -100 || F < 100) {

      C = FCR * (F -32);

      printf ("%f F ==> %f C    ", F, C); 
      printf ("%f", F);
  }
  else {
  F = pow(C, 3);
  printf ("Invalid Fahrenheit temperature.");
}
}