Defogger, couple of questions.... Options

[marco-polo]

this may have been covered in previous posts, ive been searching around and don't know what the problem is..

my defog doesn't work...
the problem is my windshield will get fogged up and the only way to clear the glass is to turn on the a/c...
my rear defog works great without any problems.

also another problem i have is the heater doesn't work either, like i mentioned before my a/c works great, the weather is pretty cold and a heater would be great.

Thanks for any help or recommendations in advance i greatly appreciated....

[marco-polo]

1) thanks, have a better understanding of that.

2) what is the average cost to replace the heater core so i know what i'm getting into and how much money to gather? (if known)