psr 42

Hope someone can help, Recently started noticing an occasional acrid burning smell that comes from the air vents , and also can smell it under the hood but cannot pinpoint it , it seems noisier than usual but again I cannot tell if it the steering pump or alternator, At the same time as the smell started the increase in noise was very noticible from the left side of the dash , Sorry to be vague but it is driving me mad trying to find the problem