What could be the problem

Smoke can be of different types and the color tells you something.

White colored smoke indicates steam (water/coolant), black colored indicates burning of carbon based materials (maybe a belt is turning on a pulley that is seized and this would emit squealing noise if you rev the engine) and grey (bluish tinge) is oil being burnt.

Smell is another indicator, none means steam.

First thing you need to do is check where the smoking is coming from. The exact location is required to understand what is causing it and necessary rectification methods.

When engine is cold, check the coolant level in radiator, ensure it is full and reservoir too. Engine oil level.

Is the A/C working?