I'm putting together a long resto project (68 B body) and am in the middle of installing the dash. As I replaced the harness with an M&H piece, I'm testing all of the electrical bits before bolting the dash in for good. The question I have is with the fan motor, when I turn the ignition switch to run, the fan switch on the heater control gives you a low speed, medium speed and a high speed but no off, regardless of the switch position. Is this normal ? I can't say as I remember. This is a heater only car (no A/C ).
Thanks

Mine turn off, whether 68, 69, or 70.
Maybe I should say they stay off, because I can't recall the last time I used heat/defrost in one of them.
Whether that's accomplished with the switch itself, I can't say.
But that would seem the easiest way.

i have a 69 b-body.fan shuts off

First guess is a defective switch if they don't turn off.

Does your fan switch have 4 detent's? As I recall the fan switch should have off, low, med,high, 4 detent's.

It turns out the switch was not seating fully in the off position. It felt like it was, but electrically, not so much. Exercised it a bunch of times and all is well.

Thanks for the replies.