I got my integra only a few months ago and throughout that time the temperature needle has never moved from the bottom of the guage (maybe minimally but very very little). This was until the other day until it went to almost halfway. I had just gone up a small slope in first (high revs with little air cirulation) and my car was filled with a pretty nasty smell (definitely from too much heat, burning coolant possibly, not oil, and definitely from the engine, not flatulence ). After looking things over I'm pretty sure the radiator is fine though I know integra radiators are less than congenial towards their owners. After driving a bit I noticed it only heats up when idling probably from lack of air circulation... I checked the radiator fans and they never once came on at idle until I flipped the AC on and both came on so i know they work I think the switch is out... does anyone know if my guess is correct? and also, where is this switch? is it hard to replace? is it expensive?

Note: I did look for coolant leaks and found none. All the hoses held pressure until the engine cooled.