the heater works great upfront, but what would cause the rear vents to blow cold? i have the heat on high upfront and the rear controls set on high but they blow cold, how do i fix that?

 

Are u positive you have rear heat? Mine only has AC in the rear

 

why wouldn't the rear have heat?

 

98-00 had rear A/C only, 01-03 had rear heat and a/c. Someone else will have to help you more, but th first thing to do is make sure both hoses going to the rear heater core get hot, otherwise you may have a blend door problem too.