Rooftop Warm Air Diverting Fin???

From my recliner at home, the roof of our 08 PC2350 is visible out the window. It had been covered with about 4 inches of snow since a few days after we purchased it and brought it home. Last week however, we had several above freezing days and the snow has gradually melted revealing the usual RV roof top items, but one has me puzzled, a 3 to 4 inch tall, 12 to 15 inch long plastic fin maybe an eighth of an inch thick. It's oriented fore and aft and is located about half way between the roof top AC and the roof vent for the refrigerator. The only possible function my feeble mind has come up with is perhaps to divert warm air from the refrigerator vent being drawn into the AC cooling vents reducing it's efficiency. Can anyone confirm this?

I can't imagine any use for it.  My *guess* is that's not a factory item, that a previous owner put it there.   Maybe a support for a solar panel or some other rooftop add on.  I would see zero value in trying to divert the refrigerator exhaust air from the a/c, but that doesn't mean a previous owner didn't think it would help.

Vortex generator ??

Or maybe to divert condensation from the air conditioner away from the the slideout  opening. It looks like someone added an extended gutter spout at the front of the drip rail too.

DON'T remove that fin!!!

I have the same fin on my 2007 2350 shown here.

I asked Kermit Fisher about it many years ago.  Kermit was the founder of Phoenix USA and sold the company about 4 or 5 years ago to the current owners.  That fin serves a very specific purpose though I can't remember the exact details.  I want to say it has to do with wind turbulence related to the a/c unit affecting the roof top fridge chimney.  If you have an older model 2350 with a stationary fridge (NOT inside your slide out) then you have a roof top fridge chimney like Old Mainer and I have.  I believe the relationship between the a/c unit and the fridge chimney requires that strange fin to prevent a chimney downdraft when driving.  Without the fin, the down draft will cause the fridge to malfunction.

The fin might also divert condensation away from the fridge chimney.  Like I said, I forget all the details.  One thing certain, that fin serves a specific purpose and should NOT be removed.

It would be interesting to know if anyone who owns a 2350 with the fridge inside the slide out, also has that fin.  This because the fridge chimney is located on the side of the slide out near the top to work with the moving fridge.

Other models of the same era might not have that fin because the a/c to chimney relationship is different.

Thanks! I love this forum.

This is all crazy talk. Clearly, this is an inverted keel, and it is there for high speed, aerodynamics and handling.

Please tell more about your new thermal camera

Last fall I tried 4 different infrared cameras that connect to an android phone via the USB plug. 3 of them were basically the same device internally with a different brand on the outside.


The 4th one was a little bit more expensive but far better. Its images are clearer. They real time refresh as you move the camera. It adds a thermometer color legend on the side that auto scales from the coldest part of the image to the hottest. Resolution is 256x192 and seems to be more than double what the other cameras produced. It also captures video. I also thought it has the best app interface of the 4 that I tested.


The IR camera is TOPDON TC001
TOPDON TC001 Thermal Camera for Android, 256x192 IR High Resolution, Thermal Imaging Camera, Thermal Imager - 25Hz Refresh Rate, Video Recording Supported, Works for Smartphones and Tablets & PC https://a.co/d/38YuQiD


I found it on sale for just under  $200. I think the price is higher now. During prime days it was $240-something.


I initially bought it to see where I needed to insulate my PC since I visit relatives in Illinois in December (low teens at night) and I live in Texas (over 100F in summer). But I also use it to ID insulation issues in my house & garage.


Also.. If the temp difference btwn inside and outside is at least 20 degrees, you can use it to see "In" or "thru" the walls.  Not see people, but the construction of the wall.  Attached are some photos when it was 38F outside and 75F inside.   You can see where the aluminum channels are in the walls, roof and floor.  The heat loss around the edges of the slides really stands out, the coming out of the fridge and water heater, as well as the transition walls behind the cab and the forehead cap.  Even the power cord slightly glows.


I've attached some examples here,,, but I had to drastically reduce their size and resolution in order to get them to upload.... But you can still tell from these low res samples what's in the walls and what is hot or cold.

Diverter fin dimensions?

I didn't measure it before installing it.. But from the box it came in...
20 inches long
3.5 inches tall
1.25 inch foot (the bottom of the "El" shape)
Approx 1/8 inch thick.


If I were to make one, I would add 4 to 6 more inches in length. From the IR photos the spread of the hot AC exhaust is a bit wider than the baffle is long. I chose to not center it. I mounted it as close to the shower skylight as possible to protect the rear side of the fridge vent which is the end with the coolant heater tower.


Also, I was curious if the baffle has affected the AC performance. I started it with indoor and outdoor temps at 97F and the fan on high.   2 hours later the indoor temp had dropped to 81F.  I normally get no better than 6 or 7 degrees per hour in full sun, but today was partly cloudy, so I would say all is normal.

Interesting to learn about the fin.  The thermal pictures illustrate that it performs.  Removes all doubt about what it is there for.  Now, I know.

I remember the sales rep (back in 2012/2013) telling us the baffle was added because the AC would blow into the vent and blow out the refrigerator pilot light. If true, the heat deflection was an unexpected (and possibly unknown) benefit. Those thermal pics are awesome!