Mod for better fridge cooling in Clamshell T@Bs.

gregndeb

This may end up being a fairly long post.  The fridge in clamshell models is a 2-way.  There have been other discussions about cutting holes in the cabinet to allow better airflow, but the source is the hot air exhaust at the bottom of the fridge.

Theory:  The fridge is essentially like a home refrigerator:  Cold air is drawn in on one side of the front, hot air exits the other side, also in the front.  The area within the clamshell kitchen is sufficiently small that the hot and cold air mixes, causing the fridge to work harder.  Most people with clamshell fridges leave the clamshell door open slightly to allow better airflow.  This mod will enhance that airflow to and from the fridge.  It will consist of 2 parts: getting a good supply of cold air to the fridge and a way to direct the hot air away from the fridge, to the outside.  It will also allow the clamshell to be closed for extended periods.

Getting better cool air to the fridge:
This was the easy part.  I had previously added a 2-odd inch hole for the factory fix of adding more intake air.  I just added a second hole.  The diameter was 2-3" holes under the fridge to the outside, then adding appropriate cover to to prevent water and bugs entering.  The factory fix was a "horseshoe" cover, but I added a different cover to figuring it would keep water out better.  (There's a picture of the cover and it installed.  I have also shown the inside of the fridge cavity within the cabinet.  Note the 2 extra holes bringing in cold air.  What is important is to get cold air to the back of the fridge cavity, where the fan will then blow air over the hot coils of the fridge and out the front.  The "factory fix" intake I added on the left.  The one I recently added was to the right, outside the frame rail. (with the light shining in it)




Once I got the added cooling, I could reinstall the fridge.  Then I had to figure how to do the next part.


Ducting the hot exhaust air:
Background.  I saw Richard England's mod at uCamp 2019.  He had a small prototype "chimney" along the left of the fridge door.  I made one too.  It did help the fridge cooling, but I wanted something better!



Ducting the hot air out of the T@B:
This took me awhile to figure out.
I made a sheet-metal duct to capture the hot air exiting the left-bottom side of the fridge.
The duct taperes away from the fridge, to clear the cabinet.
I then cut about a 4" wide by 2" tall hole in the INSIDE side wall of the T@B.  (Not for the faint-of-heart, but it's on the inside!)
I cut a (roughly) 4" x 4" hole on the outside of the T@B to pretty-much line up with the inside hole, and give a path for water to drain, if needed.  I then removed the foam between the outside and inside layers.  Then used aluminum duct-tape to fashion a duct within that wall cavity.


It kind-of looks like a recessed toilet paper holder, huh?  The outside location was purposely located to clear the clearance light and reflector.  Also if water gets splashed in the vent, it will drain out easily.

I then used a "dent vent" to be used as an actual vent.


The duct was interesting to make too.  I used 0.020" thickness aluminum.  I wouldn't want to go thicker.  If I try this again, I suspect I would try with thinner material. 
This is the rear view, top side up.  Note the inlet is not the full 2" height, but there is a flange that goes under the fridge to capture most of the hot air.  I also have a mounting tab, shown on the right, which will go to the left when mounted.  I was going to screw the duct to anchor it, but the tab catches on the inside of the cabinet.  It's an easy press-fit.  The duct is easy to remove too.

The duct protrudes in the outside duct slightly.  I will be adding trim around the duct to better keep weather from entering the clam area.  

That's it for now.  Thoughts?

Vikings

When we 'boondock' frig sucks too much power from battery, and essentially becomes a storage cabinet.  
To help I want to install two six volt batteries and will eventually. 
But I would like to hear if you think your fix changed operation/power consumption of frig. 
Finally let us know if water infiltration while driving in rain is a problem.   
Thanks.  Your 'faint of heart' comment was appropriate!

Sharon_is_SAM

Nice job!  Smart to vent it to the outside.  Your new floor hole goes beyond the corrugated cover.  Surprised the factory did not extend their opening in the same way.  

gregndeb

I have not measured power usage.  Richard England is the guy at uCamp that had the "chimney" idea.  He claimed that his electric usage went down some healthy percentage (I don't remember the number, but it was enough for me to do that mod, then add my additional mods.)  I am surprised by how warm the sheet metal duct gets as it is venting out.  (Good thing that the heat is going out and not heating up the intake air!)

I intend to put a piece of wood as a trim piece.  I will seal that to the outside duct area to prevent water coming in.  The inside duct removes pretty easily, so I'll keep an eye on it.  I may even remove in cold weather and put a piece of foam to block the outside vent outlet.

The "factory fix" inlet was inside the frame rail, somewhat near the spare tire.  It was also outside the corrugated cover.  I think that 2 inlets is needed for cool air.  It is better to have too much intake air than restrict it and have other issues.

Marceline

Could you provide information about the cover that you put over the underbody vent to bring in cool air? I have an early PV-manufactured T@B and I think that I might not have any vent.

gregndeb

The "factory vent" was a black horshoe vent. 

Here's a link to the one I found on ebay.  (That was a tough one to find, then I didn't use it)
https://www.ebay.com/itm/262534130862

I honestly don't remember where I got the other vent.  (I like it a little more because I think it has more "splash protection"  I did find this one on etrailer:


Here's a link:
https://www.etrailer.com/Accessories-and-Parts/Redline/HMAV2.html

I modified each vent, for my installation:
The horseshoe vent I added screening to keep mice and big bugs out.
The half-moon vent I made the slots a little longer, to allow any potential water to drain out.  

gregndeb

Regarding venting the fridge in general:
The 2017/2018 Clamshell with the Norcold fridge did not have any extra venting.
There was a fix to (allegedly) prevent condensation on the back wall of the fridge cavity.  (The condensation would occur next to the matress/passenger-side seat.)  NuCamp added insulation and the bottom vent.  I installed that fix.  It didn't do much good.  I posted a larger mod to correct that problem.  here's the link to that mod:
https://tabforum.nucamprv.com/#/discussion/8311/320-cs-clamshell-refrigerator-condensation-causing-moisture-on-inside-wall-and-bed-cushion

I wanted to ensure I had sufficient cold air being supplied to the fridge, especially I was blocking the typical air inlet on the front bottom of the fridge.  Thus I added the 2nd half-moon vent.

So far it is working well.