funky smell from AC... ideas?

**sausagepatty** · 04-06-2018, 08:56 AM

hello all,

my wife and i full time in a 2017 312bhts tt, purchased new. we just recently moved into a new spot, and now notice that, when running the AC, the interior of the trailer smells faintly of the black tank - aka the trailer smells like crap. the smell fades when we stop the AC. i have no idea why it would do this, and it has never done it before and we've been using the trailer and the AC regularly for about 3 months.

any ideas as to the cause, and possibly, a fix?

thanks all

sausagepatty

**jkwilson** · 04-06-2018, 09:17 AM

I'd pull the grill of your AC and see how the return air side is sealed. If it can pull air from the attic area, it might be able to draw gases from the tank vent.

**howson** · 04-06-2018, 09:28 AM

To expand on what jkwilson posted, I suggest you read through this very informative thread: https://www.mygrandrv.com/fo...nditioner+duct

**Steve7** · 04-06-2018, 09:50 AM

Interesting you only notice it when the ac is on. I like the two suggestions so far. It may also be the air admittance valve (aav) under one of your sinks these went bad this occurs sometimes very quickly after purchasing. It then emits the sewer smell. They are easy to replace, and many put on a better quality valve that can be found at Home Depot or Lowe’s.

Look under your sinks and they should be at the top of a plastic pipe near the top of the sink. See if they smell under there. The ac may be drawing the foul odor out in the air return.

**Hawaiian Punch** · 08-05-2022, 10:29 AM

Originally Posted by Steve7

Interesting you only notice it when the ac is on. I like the two suggestions so far. It may also be the air admittance valve (aav) under one of your sinks these went bad this occurs sometimes very quickly after purchasing. It then emits the sewer smell. They are easy to replace, and many put on a better quality valve that can be found at Home Depot or Lowe’s.

Look under your sinks and they should be at the top of a plastic pipe near the top of the sink. See if they smell under there. The ac may be drawing the foul odor out in the air return.

There wasn't / isn't any odors coming from under the sink, but I went ahead and replaced the two AAV's anyway to see if it helped .... it didn't. Thank you for taking the time to respond