Yes, you can get black dust on your wall from a baseboard electric heater. If the heater has a fan, this often spreads dust to areas near the walls. If the heater does not have a fan, the warm air rising from the heater can cause dust to settle near the area.
would the fan belt on a v8 motor cause squeaking
fan belt needs tightened
no
Belt is loose and slipping
A black ceiling fan is likely to show the same amount of dust, unless the dust is dark in color. For instance, it could be mold spores or soot particles from candles. In this case a black fan will be less likely to show the particles.
The most likely cause is the fan belt is slipping
On my Mercedes sprinter the cause of the fan belt vibration at low idle speed was the pully on the alternator.This pully should ratchet in one direction.
Besides having the p/s fluid cause the belt to slip, the p/s fluid will eventually ruin the belt.
Shadows have an electric fan. All engines are FWD. Hence the engine is sideways. No belt turning a fan. So whoever told you a fan belt was the problem is mistaken. More likely the cause is a timing belt.
If the whine happens when starting to move forwards, and then stops once the vehicle is moving, it could be caused by a loose fan belt. If so, tighten the fan belt, or replace the worn belt.
You may have a serpentine belt on that car. I believe they had an electric fan. The serpentine belt is black and you can see it by your alternator, A/C compressor, etc. Under the hood of your car should be sticker on how to route the belt. You can look at that sticker and then see where your belt goes. There is no fan belt on a 1991 Nissan 300zx. The fan is directly driven by an electric motor. The water pump, alternator, and air conditioning compressor are belt driven. The belt for those components is located at the front of the engine.