Is it a wall AC?

its a window unit; sorry i should have mentioned that

The indoor (or evaporator) coil, where the heat exchange happens, needs cleaning. Or if it is new, it has DSS "dirty sock syndrome".

I take my hat off for you Vith,once for figuring out that it was a window unit then again for telling him what the problem is. IMO anyone that trot's out such question and omit's such highly relivant information doesn't deserve help.

OP said new unit stinks also. Must be bad. Return it for another new unit.

Why would a brand new unit have dry sock syndrome. Doesn't that take time to develop?

Actually from what I have read DSS can happen with new units using recycled metals and the "stink" comes from the recycled metal. (Think landfill smell)

I have also read the only way to guarantee no DSS is a coated coil.

I have this same problem in our home with normal HVAC, only the master bedroom smells. clean ordorless air is coming from all other vents. could there be a dead animal that penetrated the duct nearing that vent for the room? just curious of this could be the reason. there is a small gas heater in the bathroom for that room but the ordor i smell pretty awful.

I have this same problem in our home with normal HVAC, only the master bedroom smells. clean ordorless air is coming from all other vents. could there be a dead animal that penetrated the duct nearing that vent for the room? just curious of this could be the reason.

It really needs to be investigated. It could be a dead animal, it could be sewer gas, nat. gas leak among other things.

Typically DSS type problem is distributed throughout the home becase the smell originates on the E-coil due to bacteria. Because of that your problem doesn't sound like DSS.

Does yours smell like musty dirty sweaty socks? Rotten eggs? how would you describe the smell?

If the HVAC supply grills in a bathroom are located in the floor, overflows from toilets and tubs can get into ductwork. High humidity in bathrooms can also be favorable for the growth of mold and mildew. I suggest the first thing to do is a visual inspection of the inside of the ductwork working backwards from the supplies in bathroom. You can do that with a fiber optic camera.

You can purchase an inexpensive fiber optic camera that works with some cell phones and tablets from Amazon for $20

https://www.amazon.com/Inspection-Waterproof-Borescope-Adjustable-Android/dp/B08X1X82DD/ref=asc_df_B08X1X82DD/?tag=hyprod-20&linkCode=df0&hvadid=533457287269&hvpos=&hvnetw=g&hvrand=4181918499004419858&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9008382&hvtargid=pla-1416820149314&psc=1

Thanks for the responses. i think i figured it out. i actuallu stuck my face in front of said vent while the AC was on and to my surprise it smelled clean like the others vents. So immediately felt better and knew it had to be originating from the bathroom and the small old 30 year old heater likely has a leak. That bathroom also doesnt have any sort of exhaust fan or HVAc vent; luckily it has two windows. So i closed the door to that bathroom and put a towel at the base of the door just expirement and waited a few hours and usally i can smell the odor that was driving me nuts in the hallway and this day while i had the bathroom door shit for that room there was no smell coming from that room. so now i do feel so much better that our central air is working properly. so i will replace the hoses for that heater if not get rod of the whole thing altogether. just wanted to share in case some else has a heater in their bathroom and out ductwork is in the ceiling.

That bathroom also doesnt have any sort of exhaust fan or HVAc vent; luckily it has two windows. So i closed the door to that bathroom and put a towel at the base of the door just expirement and waited a few hours and usally i can smell the odor that was driving me nuts in the hallway.

Yes, that's what I mean about investigating. DSS originates from the E-coil. So the odor in that event will be prevalent through out the structure.

Bathroom type smells are *different* --- like if return air is near a bathroom the door is left open. OR if someone was stupid enough to put an air return in a bathroom. But crap type smells do not equal DSS. They are different odors and smell different.

Natural gas type smells (rotten eggs smell) can be confused sometimes with bathroom type smells. Methane gas (sewer gas) can confuse some people as these smells are similar.

Thanks for posting as there is another thread currently debating DSS or other smell type problem that is different from yours as it's stated as coming from all ducts. That is often the key point in much of this as finding origination of the smell is the key to finding the solution.

You don't get there without investigating.

Hello, I know this is a super old post but...I'm having the same issue except I live in an apartment building with central air. When the AC is running only one bedroom smells like cat pee. A lot! Other rooms and vents smell fine. It's driving me crazy and I don't know what to tell my maintenance guy in our building other than when it's running this awful smell fills the one room. When you turn it off, and run the fan everything is fine and doesn't smell. Sometimes it's even off and on. It will smell fine for a day or two and then just revert to stinking like holy hell. We have never had maintenance check anything out in the 6 years we have lived here. And this is the second summer where we have experienced this strange stink. Can someone please help?

I'm having the same issue except I live in an apartment building with central air.

Depending on what, where, how, when, why --- your apartment could be surrounded by other apartments, with other people and their living habits. Typically an apartment is separated by a sheet rock wall... there could be small cracks or gaps at the base of those walls, thru flooring possibly and or other possibilities. (They are often built *cheap* for the lack of a better more beautiful word that someone won't be offended by... *usually the builder or the apt. owner*)

I say this because we might draw a builder into this conversation. LOL. (fine dining, fine accommodations, contractual obligations don't spell anything good for apartment owners.)

When AC / Heat turns on in your apt. as well as other apts near yours the rooms of such are blown up like balloons and in some cases sucked into a vacuum drawing air anywhere from whence it can get it.

If one apt is blowing and another apt is sucking? GIGO.

Garbage In / Garbage Out... the net result is more or less smells collide among other things like odd noises.

This is yet another reason why apartment living isn't for everyone. Not to knock you, but to give you context as to WHY?

When I working in home health care, a client had a house with a bad smell we couldn't pin down. We looked everywhere. Figured it had to be the big wall conditioner that was pretty high on a vaulted wall. Had it serviced, no change. It turned out that a roommate put fresh broccoli on top of a kitchen cupboard and forgot about it. The odd thing was you couldn't smell it in the kitchen. It seemed to smell in isolated places. And 3 feet away from the smell you couldn't smell it.