We live in an apartment with Central heating and air. It seems to work about as well as other apartment ACs meaning that they never work very efficiently and always have higher than average bills. My question is regarding a smell that is not coming out of the room vents. I have discovered that it is actually coming out of the large air uptake vent inside our home. I have bought a 12MERV 3M filter to replace the cheap one that the apartment complex uses in the uptake vent, but that has not gotten rid of the smell. It tends to happen more once the air conditioner has cut off. My husband thinks it smells just a little musty or dusty, my girlfriend thought it smelled like something was overheating, and I personally think it smells like some chemical smell. I know it's not mildew. Whatever it is, I am getting headaches and that's the only thing I can think would be causing it (We steam cleaned the carpets ourselves when we moved in, in addition to their professional steam cleaning, we have a hepa filter in the bedroom and we also have a sharper image ionic breeze in the living room, so we're pretty free from allergens). Any ideas would be extremely helpful. Is there anything we can do on our own to clean the inside as I suspect it is coming from just inside the grate/vent and doesn't smell in the actual vents that the air is being released from. I'm worried it might be dangerous. We've had the apartment check on it, but they say that they can't find anything wrong with it. Thanks!
Abs

I have exactly the same problem. I do not think I can live another day in this hell! I've been having this problem for 6 months now. My landlord says he is trying to fix the problem! Nothing! 2 months ago I discovered that this smell is coming out of the apartment downstairs. I believe my neighbor is making some sort of the substance there. I called police, landlord, and they do not do anything about this issue. I live with my 11 y o son. He cannot sleep during the night. Maybe you were living next to same person? I live in "Via Ventura" apartments on Hayden & Via de Ventura.