yeah, having an air filter near your fog light isnt the best place, might suck up some water or something :\ a fine mesh is probably safer. just plug in a mini fridge into the cigaret lighter and open the door when you want some cool air
most aircon rads are big, and if you found a smaller one you may need to change the aircon pipe connectors ect and you might have to extend pipes. possibly a lot of work lol