Wiring blower motor to a switch?

[Rob68c10]

Hey guys I am going to be replacing my heater core and cleaning out the box to get some heat in my truck. I'm not restoring it, just want to get it working for a show next weekend that is by the ocean. Would be nice to have defrost on those cool mornings. Anyways, my fan lever is broken on the controls and I was wondering if I could just wire the fan up to a switch and have it just one speed?

Thanks