Trying to understand Refrig fans - inside and out

[TundraTower]

I installed a condenser fan kit on my trailer and saw a very big difference. I would like to further optimize my cooling but have some questions:

1. For those of you with condenser fan, do you run it when you are traveling down the road and running refrig on gas? Seems that the small fan is insignificant in that much wind. On or off in transit?

2. I am trying to understand the clamp on fans on the cooling plates inside the refrig. Which way do those clamp on fans blow? Are they sucking air away from the cooling plates, or blowing into the plates? The cooling plates are bordered by the back and sides of the refrigerator, plus the top of the refrig and then the drip pan underneath. So, the cooling plates are basically in a 5-sided box, making it very inefficient to "circulate" air in any direction. Do you have to modify the drip pan to maintain an air gap at the back (mine slides front/back) to create an air path?

3. The inside clamp-on fans only impact maybe one fourth or one third of the cooling fins due to narrow width. Does anyone make a fan assembly with a plenum that attempts to blow (or suck) air across the entire row of cooling fins?

4. The inside fan would seem to accelerate heat loss when the refrig door is open. Has anyone tried a control scheme where those fans cut off when the door is opened?

Thanks for your help.

[Joe417]

1. I have a thermostatically controlled condenser fan. Require by Mfgr when frig is horizontally vented. When it failed last year, the frig worked fine while traveling but failed with a "No Cooling" error each time I stopped for a couple of hours. I replaced the failed fan and added a second manually controlled fan as a backup. They help.

2. I bought the small double evaporator fan that clips on the aluminum fins. It blows air toward the cooling fins. It helps keep the frig at a more even temp but I found it a pain in the... Items in the frig hit the fan and caused problems. The battery powered camco used 2 D batteries and last a month or two. Sits on the shelf blowing air up and I've found it does as good a job. And items touching it are no problem.

3. When I was investigating the fan issue, I did find one that mounted on the inside roof of the frig, sucked air in the bottom and blew air out the back which then traveled down through the cooling fins. I believe it was $60. Search the internet. The $12 battery powered on the shelf model works well and made the wife happy.

4. I haven't experimented with it, but I think that once everything in the frig is cold, the cooling capability can offset an air dump within reason, especially with the fan running. It circulates the warmer air and cools it quicker than convection.

That being said, I don't think any frig can offset the door holding capability of young kids and... some adults.

[Sandia_Man]

No outside fans installed on our fridge and our dual fans on the inside are mounted about center on the fins. The dual inside fan just needs to move lots of air and discovered that they are considerable more efficient than the small battery powered stand alone units that we initially used. Our Dometic has performed well from day one, adding the dual interior fan reduces recovery time and keeps temps consistent throughout the unit.

No need to have interior fan go off every time you open the door unless there is cause to keep it open for more than a couple of minutes. Yes, cold air does escape but that has little effect on the temp of all the items within your fridge. When door is closed the dual fan allows quick recovery with the help of all the cold items within. Ours runs 24/7 whether we have hookups or when camping off the grid, current draw is minimal and has little impact on our 12 volt reserves.

[john_bet]

My outside fan is built in at the factory so I can not control it. It runs when necessary. I do not have an inside fan and our stuff stays cool just fine.

[Dutch_12078]

Our outside fan in the roof vent is thermostatically controlled, so it only runs as needed. Our interior fin fans, two sets of two, cover almost the entire fin section, and run continuously while the fridge is turned on. Since adding the fin fans, the inside temperature is very consistent top to bottom, and we can run the temp setting at a lower number (warmer setting) than without them.

[midnightsadie]

just move the inside air, and outside I turn mine off when moving ,the wind does the air moving outside.

[dougrainer]

Hot air rises. Same principle on the INSIDE of the refer as on the OUTSIDE. On the inside, with NO extra fan, the convection air rises from the rear up and thru the Evap fins and then hits the top of the refer and flows over forward and down the front, removing the heat from the items in the refer. That is the design of a absorbsion refer. Also, that is why it is CRITICAL to NOT have block type food or plastic baggie type food against the REAR wall of the refer. That will stop the normal flow of air up and over. You want a 1 inch gap to help air flow. So, following this principle, you want your added inside fans blowing UP from the bottom. Doug

[RJCorazza]

On my last rig I zip tied a muffin fan to a middle shelf blowing down. IMHO any location is acceptable to move air around in the box.

[Halmfamily]

My outside fanss are on a thermostat and the interior dual fan lays on the top shelf blowing air down, found this works better than attached to the fins.

[SCVJeff]

You will hear all kinds of stories on exactly where to mount a fan in the fridge, but at the end of the day the whole point is to circulate the cold air being generated into the box, exactly as a residential fridge does. The air is constantly moving so the food is more consistent with no cold or how spots.

My fan is not mounted on the fins because all that does is single out specific places to draw the cold. Mine circulates the air clockwise in the box, and that naturally draws cold air off the entire assembly and draws the warmer back up to re-cool.

My fan is wired to shut off when the door is open just like a residential. Depending on which make and version the fridge is you may or may not be able to wire it to operate that way.