Do you know why the heat hasn't been working?
White smoke and burning smell that quickly dissipates suggests a short in your wiring somewhere.
If you have spent any time under the hood of a car, check all of the wires in the engine compartment. Look for blackend connectors, exposed wires (that means the wire is insulated except for one or two places where you might see scorching), loose wires, etc.
Where there is smoke and a burning smell, there is fire.
Get it checked out now. $60 or so spent to have it looked over is cheaper than the $500 deductible, loss of personal items and possibly loss of life because of a major fire.
(I'm not a real mechanic; I'm just old
and have learned the hard way. If a real mechanic tells you something
different, listen to him and fuggedabowt my answer)