Isn’t this normally a resistor failure ?
https://www.youtube.com/watch?v=CujvawXsjDA

@gary yes thanks, that video helped me a lot. i think that may have been the initial problem with only blowing on max, but didn’t fix- something else caused total failure.

I then focused on the heater control panel as suggested and measured voltages there- still nothing getting through.

so it had to be the ignition, right?

and it was!! I’ve just connected a wire between red and yellow from ignition at the fusebox and it now blows like a beauty! no more fogged screens. thanks all