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Old 07-05-2023, 01:26 PM   #1
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Cleaning ductwork

Hi all, I posted the following question in the New Members Forum and got 0 answers. I figure either it's a dumb question, or I used the wrong forum!
We have a 2019 Montana 3121 RL. In the last few months after we've run the two AC units, I've noticed what looks like black dusty stuff appearing on surfaces throughout the unit - size ranging from mostly dust specks to maybe 1/4" at largest. It looks like dried pieces of mold. Nothing inside is mildewed or moldy, which leads me to wonder if the AC ductwork needs cleaning. We've never had to do that in past 5th wheels we owned, but this is a bigger unit with 2 ACs. Have you found that ductwork is something that needs periodic cleaning? Thanks!
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Old 07-05-2023, 03:03 PM   #2
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I don't remember a thread on that topic - but there is always a first I suppose.
I cleaned my AC filters this week and noticed a few bits of sawdust on the top side. I had never seen sawdust on them before. I was up on the roof washing it 2 weeks ago and maybe I jarred some dust loose.

If you can post of pic of the black spots and maybe pinpoint the location you found them - it might help identify what they might be.
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Old 07-05-2023, 03:12 PM   #3
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Yes pictures would help. The only thing I could think of might be the foam insulation used at the base of the AC units. I don't know if you can "clean" the ducts. I'd start by removing the covers and see if you can see any black foam. Ozone damage to the insulation could be a cause. Keep us posted please.
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Old 07-05-2023, 06:06 PM   #4
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Any chance it's the foam air filter breaking down?
Maybe remove the AC unit cover and check the coils. They may need a good cleaning. YouTube has videos on how to clean your AC coils.
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Old 07-06-2023, 08:58 AM   #5
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Update on ducts

Hi all, thanks so much for your replies! We actually took our rig in for some unrelated minor repairs yesterday, so I couldn't get pics for you. We did ask the tech if they could blow out the ductwork & check the ACs, so perhaps that will do the trick. BTW, I regularly clean all the filters that I can get to inside the rig, so those are not causing the problem. Will provide an update when we get the rig back.
Wanted to add that I didn't find sawdust in any of the filters, but perhaps they'll find some in the ducts. I know residual sawdust is a problem in Montana's. After owning the rig for 4 years we still find some sifting down from the vent over the stove!
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Old 08-31-2023, 09:31 AM   #6
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Hi all,
Thought I'd post an update to my question about cleaning A/C ductwork in our 2019 Montana model 3121 RL. We had our rig in for some warrantee work and general maintenance. I described the problem and showed them the black specks & chunks that were showing up on all surfaces. The techs said they could blow out the ductwork (they advised against using anything other than blown air because of the risk of tearing the ductwork). Since they were replacing the bedroom A/C unit under warrantee anyway, they kindly didn't even charge us for the cleaning. Since we have the unit back home the air is clean again. Just thought I'd let the hive mind know that ductwork can be cleaned by blowing it out! As I think about it, I wonder if the malfunctioning A/C unit might have been contributing to the problem. At any rate, things appear to be working properly again.
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