Ok so 2000 1.25 fiesta zetec, heating is jammed on hot no matter what setting the dial is on.

I have changed the control valve twice, i know they both work.

Previously in the past it has been the panel so i got two new ones, they smoke when installed, one just doesnt work at all. I am worried this could cause a fire so i have removed the panel but the cabin still gets really hot.

What can i do to fix this? all the fuses are fine, i dont see how there can be a wiring fault anywhere because theres nothing for the wires to rub against causing them to break etc. The connector block is fine and not melted.

Is there a way to fix it or do i have to scrap the car?