The light bulbs will be dim. Both the backlight and the warning lights. Warning buzzer will not work
right either unless it happens to be a 12/24 buzzer (it might be). Replacing the bulbs will fix the dim issue.
and temp gauges will probably not read anything. Or itís possible they will read something but just not the right values. I would guess they will be way off and not usable.
The start circuit should be the same as a 12V so it should work
I would ask a dealer for advice too. They may know the tricks needed to convert from 24 to 12.