It was just recent that I drove around with my 2002 mazda protege 5 2.0L. i blasted up the heater since its winter and i've notice a weird musty smell (kinda smell like burning food lol or something like that hard to explain online) coming out of the vent. The smell occur only when my car is in a full stop or parked. When I drove away (with the heater on), the smell gradually stop. So the vent doesn't smell until i hit a red light or when parked. When I get out of the car, I noticed the same smell from under the hood. I can't seem to locate where it's coming from. :S I don't know if its a mold build up in the vent, leaked heater core, or whatever since i don't know much.

I've check the coolant level, seems normal, i don't see any leaks.

I'm not much of a mechanic so just wondering if anyone have any ideas? Also i don't have a OBDII code reader, but thinking of getting one. do you think that would be able to track down the problem?

 

Last question: probably not. The OBDII is primarily monitoring the emission controls of the engine.
The smell could be caused by small a leak of some kind that drops on hot parts of the exhaust system. While the car stands the venting system picks up the fumes, when the car drives the fumes get blown away and you don't smell it. You can't see a puddle under the car because it evaporates rather than hitting he ground.
Take it to the place that does your oil changes.