Because the resistor between the heater swithch and the heater motor is not functioning. Usually mounted on, in or near the heater enclosure. Its a common repair, and can be done by the do-it-yourselfer.
Could be, low on coolant, stuck open thermostat, plugged up heater core, faulty temp blend door actuator,
100 miles per hour then your car will blow up or over heat then blow up your choice
your car will over heat and you might blow your head gasket
Only when they blow. They don't wear out, they only blow when there is a short in that circuit.
the smoke comes out the rear of the car in a pipe. the smoke comes out only when the engine is on. you do not have to be moving to have smoke come out. just the fact that the engine is on creates smoke due to the byproduct of the fuel and energy.
your car will over heat and you might blow your head gasket
You can not get heat from cold water, The engine has to run long enough to get the water in the engine HOT. That is were you get heat from HOT WATER-- Coolent
So that a car will not over-heat and blow up
The heater in your car uses waste heat from the engine to heat the car. When the engine is not running there is no heat to distribute.
From being parked only - no.
The heating system doesn't get heat until the car warms up and the thermostat opens.
high miles, try going to auto zone and getting some stop smoke, it's an oil aditive