1999 Ford Fiesta HEATER BLOWING COLD

hi if you look at the back of your engine you should see two pipes going through the black casing where the wiper blades are and you should see a silver round shaped device with the two pipes going through it this is a heater valve if you take that off and replace with a new one you should get warm air. I just done this about two weeks ago had the same problem. if you need anymore advice e mail me. let me know how you get on.