If you mean that you are bypassing the servo altogether, because it is a demonic piece of crap that besmirches the fine reputation of our otherwise perfect cars, then I think the only way you can redirect the heat is to mess with the vents.

The default for everything is defrost, fortunately. To alter this, I think you need to get into the dash, not sure where, and manually open and wedge or tape flaps into different positions. It would be a semi-permanent thing, not controllable from the switches, which are dead anyway if you have thrown away the piece of junk servo.

I too am considering this change, if I can get my blower working again. I'd be interested in whether anyone here has wedged their vents and how they did it.

Good luck.

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Where there's a will there's a way
1978 300D