is it a fuse that makes the heater heat up. It blows air but apparently the blender or something isn...

No, the engine coolant makes the heater work and is not related to the rear defroster (which could be a blown fuse). The blend doors work by vacuum, could be a broken hose or a bad vacuum control switch.

thank you for your help..that was great!  SLC
Recently the entire cooling system was replace and flushed.  when i bought the car in may the owner said it over heated.  Did the flush, changed out the therostat and installed a new water pump.  Now, it doesn't get even get warm...any other thoughts.  I don't want to pay 180.00 (its a girl thing)  I can fix it myself if i am given direction.  KNow what i mean.

This may sound weird but my 1996 taurus gl did the same thing. I checked fuses and level of coolant and then assessed that power was continuous to the blower motor. I took off the blower after removing passenger floor cover and 3 bolts. I then tapped it and prodded it... finally I squeezed it at the rubber near the base that bulges out in 3 places. Low and behold there was an internal problem with the blower and it came on!. I now do not use the cover plate and every once in a while I give it a good squeeze.

when i bought the car there was an over heating problem.  changed the thermostat...hoses looked ok.  Then...stupid me...put a bottle of that "stop Leak" in the radiator...that didn't work.  Put it in the shop.  Needed a new water pump.
As for the heater not working...I was the blend-door. Had that replaced.  heater is still not heating up.  garage buddies are telling me that the Core needs to be power flushed because that "Stop Leak" is bad for the inner parts of the car. And....And...now it's not getting hot at all! Also being told that the cheap thermostat that was put in needs to replaced with one from Ford. Do you agree with that?   Thanks for your Time-  Loni

Replaced fuse for refrost..........not working.  thinking that the eliment on the window its self.  Haven't had a chance to really look yet.  Windows had a dark tint on them.  Rear window tint was removed before the purchase.  Maybe it has gotten damaged??  thoughts?