Fridge fan photos

[DesertDave]

A couple folks asked me in another thread about the fridge fans I had installed. I thought it best to start a new thread with the photos.

I'd heard from WTW member Dr. J. that he had measured approximately a 30% reduction in electrical useage by his compressor fridge, through the installation of some auxiliary 'pancake' fans that moved air through the condenser coil and out of the vent compartment on the rear (exterior) of his fridge. That sold me on doing something similar myself.

The first couple images resisted all efforts to change the orientation, sorry.

Here's the box front of the four pack of fans that I bought off of Amazon.

Here's the back of the box with the fan specifications

I wanted to have the fans sit inside the camper framework, so I bought and installed some lightweight aluminum angle to the camper frame inside of the upper fridge vent opening. That gave me a vertical surface to screw the fans to.

Here is a closeup of a single fan

Here is what the fans look like viewed through the vent cover

As far as wiring them in, my first thought was to use the existing factory wiring to the back of the fridge area, that was intended for the auxiliary fan for the three way fridges. While easy to find at the back of the fridge, it was not so easy to locate the other end in the battery compartment of my front dinette Grandby.

So I looked at the Dometic wiring schematic from the fridge manual (you read the manual, right?), and tapped into the power wire for the Dometic fan that is on the back of the fridge. It is powered when the compressor runs, which is when I would want the fans to run anyway. You can see my kludgy wiring connection in the photo above showing both fans. I needed to separate out some wiring on the factory bundle to gain access to the wire I needed.

I don't have any of the fancy meters like the Trimetric that Dr. J. used to measure the impact of his install, so I can't verify the results. I do hear the fridge run a lot less, and frequently my AM voltage (before the solar starts charging) sits at 12.9V when I first get up, so I am pretty sure that I have made a large decrease in the electrical draw via this modification.

Hope this helps someone.

 

[ski3pin]

Thanks DesertDave!

 

[craig333]

Fan prior to installation of the (extra) vent. Similar to yours and also wired the same.


I added that after feeling the top of the counter one day and going, I have to get the heat out.

 

[DonC]

thanks!

 

[DrJ]

Nice job Desert Dave. Your setup was even better than mine.
I believe the other end of the wiring from the factory is intended to be at the switch center on the drivers side just as you enter the camper.
I love the idea of it running only when the fridge is running. That is a fantastic idea!

 

[smlobx]

We just pick d up our Hallmark camper in Denver and they now install one of these fans on the back of their 2 way fridges standard.
Very nice!


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[DrJ]

My new Grandby does not have the same fridge fan setup that my Hawk did.
Exact same factory venting and dometic 110 litter compressor fridge.

So this last week I did some testing on my nonvented fridge.

I put a thermometer in the upper and one in the lower outside vented section of the fridge.

The upper area is constantly 10-20 degrees warmer than the outside temperature and lower vented section of the fridge.

There was plenty of sunlight to keep my solar going so battery power is no problem during the day time.

But there is no doubt that the extra heat makes even the compressor fridge run more often.

Maybe it's time to do this mod again?

 

[ski3pin]

This may be the fan from amazon that DesertDave purchased and used.

Cooler Master Fan

 

[SLEDAWG]

Desert Dave. Good thread. Long weekend with chores complete and no road trip (avoiding crazy holiday crowds) so I decided to add an exhaust fan. I have a Fleet with a 60L fridge that is the primary energy "sump for my FWC.

I popped off the cover and traced the fan wires to the electrical connections on the back side of the fridge. Ended up testing the connections. Turns out the red wire (+) is always "hot" and the black wire (-) is switched.





I cut a hole in the aluminum sheet and mounted the fan using machine screws. I also added some screening from an oven exhaust vent to prevent bugs and especially mosquitos getting in.





Fired up the fridge and It works great. Nice discharge of heat with a small fan off an old computer. I haven't hit the road yet to test the results. But based on running the system for an hour I'm confident the discharge fan will make a big difference. Next project....second solar panel! I can't stop tinkering with my camper!


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[Terrapin]

Craig 333,

My 2013 Hawk was delivered without venting for my 2-way Dometic 110.
I believe you have commented on my problem on the conversation: "Electrical Sleuth".

FWC has offered to install venting with two fairly large vents to the side which, although should solve the overheating problem, would be (IMO) unsightly. I wanted both the upper and lower vents to incorporate access doors to for keeping the fridge area clean of dust and bugs but they (FWC) tell me that they cannot use a latched vent as the upper because there is no framing for the attachment. OK, then, I'd rather add 2 of the small square vents as per your installation each with a 4" pancake fan wired to the compressor fan. The Lower vent then could be the factory vent wth access door.

Could you comment on this concept and point me in the direction of the small vents?

Thanks I appreciate any thoughts,

Ted


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[craig333]

This is the vent I used. http://www.amazon.com/Imperial-Manufacturing-PA-6W-6-Inch-Premium/dp/B002FB65G0?ie=UTF8&psc=1&redirect=true&ref_=oh_aui_detailpage_o07_s00

Two of the 4" variety might be more your style.

 

[kmcintyre]

I noticed on the fans that there are 3 wires. One is ground, one is for power, what's the 3rd wire for (the wire that taps into the refrig for a switch?).

Any close ups of where you tapped into the refrig wiring?

Thanks.

 

[PaulT]

I noticed on the fans that there are 3 wires. One is ground, one is for power, what's the 3rd wire for (the wire that taps into the refrig for a switch?).
.

As these are computer cooling fans, the 3rd pin is the rpm sensor for the computer to adjust voltage to control fan speed.

Search for "3 pin fan connector pin out"

Paul

 

[kmcintyre]

As these are computer cooling fans, the 3rd pin is the rpm sensor for the computer to adjust voltage to control fan speed.

Search for "3 pin fan connector pin out"

Paul

Ok that makes sense but how to you make sure that the fan goes at the max rpm (where do you wire it)?

 

[kmcintyre]

Ok that makes sense but how to you make sure that the fan goes at the max rpm (where do you wire it)?

Looking at the wiring picture closer, it looks like you just don't use it.

 

[PaulT]

Not using it is correct. That wire is an output sensor value from the fan to the computer motherboard so that the software knows how fast the fan is turning. The software can read the sensor and use the reading to increase or decrease the voltage on the + and - wires to change the fan speed. As you are putting a constant voltage on the + and - wires, the sensor is not relevant to your application.

Paul

 

[dakozicki]

Can you put a link to the thermal switch you used that activates the fan at 80 degrees?

 

[JaSAn]

This is the one I have been using for 2 years with no problems:

http://www.amazon.com/Thermostat-Switch-Circuit-Large-Flange/dp/B0026RSBUQ?ie=UTF8&psc=1&redirect=true&ref_=oh_aui_detailpage_o03_s00

jim

 

[Bosque Bill]

We just pick d up our Hallmark camper in Denver and they now install one of these fans on the back of their 2 way fridges standard.

Harrumph! When I complained to FWC about the compressor fridge in my, then new, 2013 Fleet running so much they insisted that everything is just fine and it doesn't need any outside venting or an auxiliary fan.

A few questions for those who have done the mod.

1. Any problems with water incursion? Such as hours of driving in the rain or thunderstorm with strong winds? Or dust incursion?

2. In cold weather camping (or high mountains in summer), does the wind blow in through the vent and into the camper via those small slots above and below the fridge?

3. Is just the large top vent enough? Looks like Desert Dave and Sledawg just put fans behind the louvers of the top vent - I don't see any reference to an external bottom or intake vent.

Bonus question: Would simply removing the blocking panel from behind the louvers of the "vent" to allow the coils to exhaust outside help.

Thanks,
Bill

 

[PaulT]

My 2014 Hawk with compressor fridge and both top & bottom external vents from factory has had no apparent/noticed water incursion. (No staining on bottom of compartment.)

As to cold air intrusion into heated camper from around fridge... Yup, it happens although not much air comes in unless the fantastic fan is pulling air out of camper. That's how I discovered the air leak. Was using fan to exhaust moist air from boiling water. Now I open turnbuckle door so my ears don't pop. Not worried about cold air incursion while exhausting moisture.

Paul