2nd AC unit - outside odors being pulled in

[Suprnova74]

Hi all,

We have a 2020 Fredom Express LE with a second AC unit in the main bedroom area. We've found that when it is on it pulls in outside odors quite proliferically. I normally wouldn't mind, but when at a rather tightly packed campsite and people using a lot of lighter fluid, it can be quite noxious. It's a dometic unit that doesn't have the option to pull outside air (full recirc-type). When I examined the unit, it seems to not have a good and solid seal to the roof. in fact the metal plate that is bolted to the roof does have some up and down movement.
I used some incense around the base of the unit and sure enough the smoke is sucked into the unit quite readily. I attempted to use some of that aluminized hvac tape to seal around the base of the unit as well as any seams that appear to have air infiltrations as well, but our past camping trip had the same issue. I'm guessing the tape lost it's adhesion due to the movement during towing.

I took it to the dealer before trying any self-repairs for the issue and of course they couldn't find any issue. The unit is now out of the 1 year warranty as well.


Should some kind of butyl tape be used underneath the whole unit? I couldn't find whether that should be the case or not. I'm pretty handy so not afraid to remove the unit in full to figure out what's going on or to resolve it more appropriately.

[6speed]

Air conditioners on RVs have a 2 year warranty. At least the ones I’ve owned have.

[Suprnova74]

Originally Posted by 6speed

Air conditioners on RVs have a 2 year warranty. At least the ones I’ve owned have.

The actual AC unit may have the warranty, but unsure if something like the installation is considered a part of that warranty. Also, there isn't time available before my next trip so would like to try to resolve it beforehand if possible.

[Flybob]

There should be a compressible seal between the external base and the roof. There are several adjustable screws that are used to tighten the base against the seal and the roof. You want to partially compress the deal but not too tight. You may need to remove the inside face as the screws are tightened from the inside.

[Larry-NC]

Originally Posted by Flybob

There should be a compressible seal between the external base and the roof. There are several adjustable screws that are used to tighten the base against the seal and the roof. You want to partially compress the deal but not too tight. You may need to remove the inside face as the screws are tightened from the inside.

What Bob says^^^

It's a foam gasket between the air conditioner and roof. Remove the inside cover and tighten the screws snug, but no further, from the inside.

[Suprnova74]

I realized i never posted the results of my research and figured I'd post my findings in case anyone else has similar issues. I took videos of it if someone needs details (I think I still have it, this is almost a year ago ).

I wound up having my wife stand inside while I was on the roof with incense and found the location for the infiltration. A small area on the driver's side of the unit was essentially open. From what I was able to tell, I think some plug was missing as i think it is spacing for an extra condensate drain if needed. I used some duct tape to tape it closed and voila, the infiltration stopped.

I've since sold my unit and got a Class C which is having a similar issue so I may be on my roof looking for similar configurations. Although this unit has Coleman instead of Dometic AC units.

Edit: found the pic. marked the hole and how the air infiltrates. I had to remove a styrofoam piece to expose this hole. taped it and fixed.