Sewers

What is the musty, sewer smell coming out of our home air conditioner?

We have tried everything, had the septic tank pumped, had the vents cleaned, replaced the plenum. The smell only comes when the AC is running. If it is not running or the heater is on no smell. Only the downstairs unit, not the upstairs. It doesn't smell constantly. Usually only when the unit kicks on in the afternoon. We have had several plumbers out and no one can fix it. Please help! We love our house but are desparate!

Public Comments

1. Check for dead bodies
2. MOLD
3. Did you replace the filter? Or are there bugs in the system? We had dead moths in ours and didn't know it and the smell was terrible.
4. it might be mold i suggest getting a new air conditioner whatever it is could make you sick good luck
5. I would say that you have stagnant water in your drain pan.
6. sounds like there maybe a dead animal, or even some of the remains(blood) or something in there.
7. Mold in the system. You'll need to call a A/C repair specialist that has dealt with mold before. This could be very toxic, so you should have the system serviced sooner rather than later. A/C units have a byproduct of water which can attract mold if not properly serviced.
8. The smell is actually mildew. The inner workings of your A/c system forms moisture and mildew. There is probably a catch pan under your evaporator where water collects to drain. Add a small amount of bleach to this. Also go to your air intake, where your filter is. Spray it liberally with air freshner or odor-ban, while the unit is running. This will distribute the air freshnet throughout the duct work.
9. could be cold water algea in the drain pan of the evaporator coil.put 1 teaspoon of bleach in the pan to kill it.Danial S.'s answer was funny but in-correct.Compressor compresses refrigerant not air,water is removed from air blowing across face of coil,not a "by-product"of compressor operation.Also,check to see if there is a "P" trap installed on the drain line leading from the drain pan,if not,have one installed.
10. Is this a window unit or a stand alone outside- sounds like it could have some moisture that is/was sitting inside & it 'soured'-or...the actuall air it draws is damp-could matter where the unit is placed- -me, I'm a bid of an odd-ball & I'D even try something like spraying that air cleaner stuff like 'ozium' {air sanitizer that reduces airborne bacteria}arround & into the air inlet as it draws in to the unit-
11. its probly stale water or a dirty filter