I Have a 2005 Kia sedona. This problem started about 3 months ago the front heater fans would randomly stop and then when i would press the nob in they would kick on. Then it progressively got worse, untill they just stopped comming on. Well long story short I ordered and replaced the fan speed control nob/switch assembly. Now they still wont come on and it is starting to get cold. What else could it be? Maybe a fuse, a relay, the blower, or the resistor? how do i go about determining what failed? any advice would be great.