i have a 1991 ford festiva, need a little help locating a problem.. i thought at first i had a heater problem but it turns out that only 1 place won't allow heat to come through.. i thought at first, "NO HEATER, AHHH s**t" but i drove the car and worked out that only through the dash does the heat not come out.. the rest of the places like windshield and legs but no main dash area. i was wondering if anyone has had the same problems and if they have a solution, could you please run me through it step by step and if necessary with photos (for locations in dashboard to help explain difficult areas, even with arrows to point out main issue area only if it's hard to see or needs to be specific)

Also, i noticed on the heater box there was what seemed to be a wire disconnected (this wire was white, so i don't know if that means anything and not even sure if it was connected in the first place, but looks like it was connected at one stage??) should i leave it or plug it in? lol common sense tells me not to, but sometimes i just can't help myself.