How do I fix the smell coming out of engine area. everytime it turns on it smells.

had this come up before seems that ac drain was way clogged off and water from ac soaked up to the air filter in there , yuk!!! it grew mold and wow it stunk kinda like a skunk, very bad 4 you to breath that as well , cleaned it all out with disenfectant and fixed ac drain (made it bigger too) wow what a job had to remove entire dash to access it

have you poisoned mice around your home? if so they can still be getting into places you cant see or find. does the smell smell like a dead animal?

if you have a bad odor,pull off the vent line from the back and see if an animal is dead there,i've found dead birds,mice and a possum,in the blower wheel of some dryers,they get in from the outside hood,once they get into the vent line and slide down they can't climb back out or if the dryer is running the wheel does a job on them.also if you had some painting or staining done this also can make the dryer smell bad.this is going by what i've found when someone complains about an odor in the dryer.hope this helps,one more thing if the motor is overheating from the dryer not being cleaned out it could have like a shellac smell,you might have to take the dryer apart to see what's stinking or it could be something near the dryer,when the air is heated in the dryer it makes the smell worse but if you find waht is causing it and remove it the smell will go away,if it is from a dead animal you can wash down the area with soapy water,you don't want to use anything with a strong smell because your clothes will smell of that when the dryer heats up.what does it smell like?

I know this might sound weird but there might be a dead rodent or other small animal under the fridge or squeezed in between small parts. This happened to us but it was not the fridge; it was the air-conditioning unit. If this has happened in your case, the smell will be really bad for a while and eventually go away when the animal has fully decayed.
Even if it is not a dead mouse, here is a good website that gives you the names of effective odour neutralising products. It's definitely worth having a look at. http://togetridofmice.com/2009/12/dead-mice-smell-dead-rat-smell.html
Good luck.

it is common to get mice or? in the blower motor, you have to drop the blower motor out from under the dash? and check for debris

Did you see any mold? Did you see any areas that are wet? TOXIC is a term that is used to describe something that is poisonous. I think you mean noxious which means unpleasant and possibly harmful. The smell of sewage would be classified as this.

Gain access to the internal area (removal of cabinet panel) of the washer and inspect for source of smell.

You will have to diss-assemble the dryer to look for the cause. I have run into that problem before, and found that a mouse electricuted himself by contacting the exposed wire terminals on the motor. When the motor warmed up, the dead animal smell was there. There are a lot of areas where a mouse could come in contact with live voltage and end up dead on an area which heats up, like near the heating element.

Does it smell like a dead animal? or just moldy mildew smell? If dead animal, get it out. If mold/mildew smell, treat it with an AC ventilation dodorizer.

I'm sorry that I don't have a solution, but we have the exact same problem with an older model KitchenAid side-by-side. Did you get this problem solved? If so, can you share what you did?