Bedroom AC Unit Stinks........BAD!

[TerribleTim68]

Okay gang,
I think I posted this one last year when I first purchased our unit. But I need to revise this one because it has come time to actually do the heavy lifting here. I've got a 5 day long stint planned at the NHRA Northwest Nationals at Pacific Raceways and that AC is gonna be important to the health and safety of myself, mainly because if it doesn't work my wife is liable to kill me in my sleep.

So here's where I am. We purchased the unit used. Once home I turned on the bedroom AC to see how well it worked and it filled the room with a wet dog smell, or maybe some old funky socks filled with foot fungus. It was bad. I opened up the bottom side of the unit to check filters and see if anything looked obvious. The filters appeared brand new, shiny white, almost like the seller had replaced them knowing something was up. Shame on me for not turning it on before signing. But hey, for the price we paid I probably would have overlooked it anyways. Now, the main AC unit in the living area does not do this, only the bedroom unit. So clearly something is going on with that front unit. Again, filters look brand new. I didn't see anything obvious inside there either, but I also really don't know what I'm looking for or at. At that point we just buttoned it back up and said "Well, I guess we'll use a fan for now and hope for the best."

Someone had said "Go up on the roof and take the top off and see if there's a dead animal in there." I'm finally in a position where I can actually get on top of it to do that, so that is my next step. Does anyone have a step-by-step of how to go about getting the top off of it without destroying it? Any images of what I'm looking at or for? Anyone done this before that can walk me through this? I have zero experience whit this kind of thing, so talk to me like I'm stupid.

I did watch a video where this guy took the cover off his and blew out his cooling fins. Are they all pretty much the same? His had the cooling fins and then a motor inside that. I'm assuming mine will be roughly the same. I read that the wet dog / smelly sock odor could be from stagnant water in the drip pan growing mold. I'm not sure where that pan is located. Any guidance there?

 

[danemayer]

The shroud usually is just mounted with 10 or 12 screws. Be careful in case wasps have built a nest. Bad to be jumping backward when on the roof.

If it stinks, you'll probably see something obvious.

 

[sengli]

What he said. I was just on our roof, cleaning everything out per my annual routine. There are like 6 screws holding the covers on the dometic AC units. Everything is out in the open on these units. I find wasp nests in mine, from them not being used much, but something else could have gotten in there. Although the covers are vented they arent wide open though. I am wondering if you dont find anything obvious, maybe there was some mold or hopefully nothing worse... in the actual roof duct work the air blows thru?

 

[dieseldog]

I had a unit get funky like that. Depending on the unit, you’ll need to gain access to the evaporator and blower. It’s filled with gunk and most likely mold from being damp. My blower was full of dirt and mildew looking stuff and wreaked when the unit would come on. Buy a good coil cleaner from Home Depot and give a good soaking to loosen it up before cleaning.

 

[NP_Chief]

We had this same issue on our last rig. When I opened the top I found an unrecognizable critter. After I removed it and cleaned everything with bleach, the smell went away. I would recommend taking a few pairs of rubber gloves and a plastic bag up on the roof when you go.

 

[jayc]

There is a foaming spray that is sold at Camping World and likely at the big box hardware stores that can be sprayed on and then hosed off to clean up.

 

[hoefler]

Remove the interior trim. Look and see if the opening is sealed off from the attic. Chances are it is not. Cut and install thin plywood, like Luan, and tape all the joints to make a sealed passage from the A/C unit to the inside. This is the return air passage, when left open to the attic, it will pull air from the attic. The sewer vents are not sealed at the roof, when the A/C is running, it pulls air from the attic, the air is then pulled through the sewer vent caps, and you will get sewer gas as well.

 

[TerribleTim68]

Remove the interior trim. Look and see if the opening is sealed off from the attic. Chances are it is not. Cut and install thin plywood, like Luan, and tape all the joints to make a sealed passage from the A/C unit to the inside. This is the return air passage, when left open to the attic, it will pull air from the attic. The sewer vents are not sealed at the roof, when the A/C is running, it pulls air from the attic, the air is then pulled through the sewer vent caps, and you will get sewer gas as well.

Okay, that's a pretty interesting response. I'll see if I can figure that out.

 

[Lynn1130]

Okay, that's a pretty interesting response. I'll see if I can figure that out.

He is correct and I think there are several threads on this topic. The roof vents become an issue with the AC and also the fans. The fans, too, will suck in air from the vents.

 

[TerribleTim68]

From everything I've read, if the AC unit is pulling air from the vent, then the roof fan would also do the same. My unit has one of those automatic fans in the main living area. I've run that fan with no windows open or anything and had no issues with the odor. The main ducted AC unit in teh living area also does not have any issues with odor. So that tells me it is isolated to this AC unit itself and probably not a vent air issue.

That being said, it finally stopped raining here in Washington (for the most part), so I'm planning on climbing up there after work today and taking a peek inside the top cover. Hopefully I find something obvious, but I have no clue what I'm looking at inside there so the whole thing will be an adventure.

 

[Lou_and_Bette]

When you can get on the roof, pull caps over vent tubes and see if there is a large gap etween pipe and roof. We had a odor similar to yours and I found we had a significant gap between pipe and roof. I stuffed some plastic grocery bags in this gap, replace vent caps and recaulked...no more odor.

 

[TerribleTim68]

Okay, so I meant to post this earlier. Finally got up on the roof last Sunday, in the blazing heat. Holy Jeebus we seem to go from non-stop rain to inferno around here. so here's what I found -

I took the top off the unit and there was maybe a small hand full of leaves in there, lots of dust, and remnants of one tiny wasp nest about an inch across. I took an air hose up with me, so after removing the wasp nest I attacked it with the air nozzle and blew everything out as best I could, spent plenty of time trying to blow out the cooling fins as well. But seriously, I have to say, in the grand scheme of things it really looked pretty clean in there. There was no water at all, the few leaves were nice and dry and everything looked pretty good. So after a good blow job ( ) I put the top back on it, climbed back down and proceeded to clean the white gunk off the toes of my shoes and the knee areas of my pants (seriously, what is the deal with that white stuff and how can there be any left on the roof).

I went back inside the unit and pulled the bottom cover off again to take another look in there. I did take a look up inside the "opening" to see if maybe the roof structure needed sealed off better like a couple people had mentioned. Everything is sealed really well and covered with this tin foil looking stick on insulation, so I really don't see how that could be the issue. We did turn the unit on and this time the smell wasn't that bad, it was almost unnoticeable actually. After a couple seconds, you really had to walk out of the room, wait a bit, then come back in to even notice it. So I'm still at a loss here, I don't know if something I did actually changed anything or what.

In the end, we took a couple Febreeze sheets, wrapped them around the vent openings (the little black grills that you point where you want the air to blow) and put the bottom cover back on the unit. Will this help? No clue. But, we have a big outing planned next week when the wife and I head to Pacific Raceways to volunteer as part of the track crew for the NHRA NW Nationals. So I'm hoping that this unit can be run without the smell because the weather is either going to be mid-50s and off and on raining or blazing hot (that's just how it goes, history doesn't lie). So we shall see.

 

[Cperk]

I know this is kind of an older post, but I’m new here and thought I could help. Does the smell remind you of dirty socks? If so, they’re is a phenomenon we call in the a/c industry as the “dirty sock syndrome “. It’s caused by spores that can get on the evaporator coil. If it’s a heat pump it can even be worse when the heat is turned on. The only solution to this I’ve found is a product called bio-fresh. It’s made by Nucalgon. Put it in a bottle sprayer and soak the evaporator coil down with it. It can actually kill the spores that cause the smell. This product has no odor whatsoever and doesn’t have to be rinsed off. Just after spraying let it set for say 30 minutes and then turn the a/c on to let the condensation rinse it off.

 

[TerribleTim68]

Okay, resurrecting what was kind of a zombie thread, but not really, lol.

It's been basically 2 years now and I'm still fighting this smelly AC unit. So, as posted in my last update:

• I've had the top off the unit. There are no critters, dead or alive, in there. There was no leaves in there either, wet nor dry. There was not a wasp nest or anything of the sort. It was probably the cleanest inside of an AC unit I've ever seen, quite shocking really. I took my air compressor and gave it a good blow job anyways and put the top back on it.
• I took the bottom all off of it and the seal from the "attic framing" looked to be very well sealed. There was no obvious way to improve on it, no holes anywhere, it was sealed up good.
• There was also no obvious signs of what might smell on the bottom side either.

I'm still stumped on this one. I've done a LOT of internet and forum searching and I'm down to one thing, it has to be mold on the coil. So here's my question, how do you get to the coil to clean it? Where is it even located? Is there somewhere where I can find a good walk-thru for this process?

Thanks gang!

 

[cookie]

Posts 7 and 11 mentioned a possible gap between the vent pipes and the roof. Did you remove the vent caps to look for and seal that gap?

Peace
Dave

 

[TerribleTim68]

Posts 7 and 11 mentioned a possible gap between the vent pipes and the roof. Did you remove the vent caps to look for and seal that gap?

Peace
Dave

No, I installed one of those Camco Cyclone vent caps a while back and the pipe appeared to have no gap in it. I'm baffled as to how the smell from the tank would get in the roof framing when it appears to be a solid tube from tank to top. 🤷‍♂️

 

[wdk450]

If this is the original AC unit on your 2008 Cyclone, it might not be cooling as well as a new unit, along with being smelly. You might want to think about spending $700 to $800 for a new top unit and changing it out, "killing 2 birds with 1 stone'.

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[dieseldog]

To gain access to the evap coil, you’ll need to remove the cover on the unit and separate the foam cover over the coil. Once you do that, you’ll be able to give it a real cleaning. I’d bet money your blower is covered in gross mold that gets damp when the unit is running and stinks up the place. Been there and done that kinda thing.

 

[TerribleTim68]

Bill,
I think you are right. After doing a few more "tests" it seems to be cycling up and down, switching from what sounds like a high run fan to a low run fan and back, over and over. It's enough to cause the generator to bog down when it cycles, and it just keeps doing it over and over. I can shut the AC off and just run the fan on that unit and it does not cycle like that, only when it is in "cooling mode".

I think something must be wrong with the unit, possibly leaking as well, which might be causing the smell. I think replacement of this unit is in the future, I'm just not sure when the budget says the future will arrive.