Auxiliary fridge fans for Dometic 8CF fridge

[Jlawles2]

They may not be tied to the control board, but instead tied to the input power supply and with their own thermostat turn on and off.

[Yoda]

They may not be tied to the control board, but instead tied to the input power supply and with their own thermostat turn on and off.

Thanks Joseph
I did look there, but did not see the red pair. I guess I need to get my mirror and bright light out and see if I can see where they go from below. Or just cut and splice as needed. Today was nice but a bit windy. Maybe II'll get an hour tomorrow.

[Scott'n'Wendy]

Like Joseph said, they just need 12vdc. The control board does not need to 'control' the fans. So the wires may tie into 12v outside the covered board or they may go to a 12v tap on the board.

[mpking]

Per your original question, the Wago's claim vibration proof connections.
https://amzn.to/3Idlnay

Before I discovered the Wago's, I've done many soldered splices with a torch and shrink wrap. Since I don't do it often I would mess up sometimes, and have to trim and redo. The wago's remove that hazard of running out of wire.

[Country Campers]

Yoda

Keith,
I have a picture on my phone that shows the red wire connected to a different wire on the left side of the fridge. I can not get it loaded but I will take a better picture when I get home. My fridge is out on the work bench so it will be easy to see where they go, sorry I did not think of this before.

Brian

[Cate&Rob]

Yoda
Hi Keith,

Several years ago, I replaced my original Atwood fridge with a Dometic which looks to be very similar to what you are working with. I took some pictures which may help. I believe the sensor in the upper right corner (facing the back of the fridge) is the sensor for the fans. But maybe for more?? . . . that is heavy gauge wire for a single cooling fan . In the second picture, you can see the light weight wires and white connector going to the cooling fan.

The red wires come across the top of the OE fan and down the left side. I presume to keep then way from the hot right side. I did not take a picture of how/where these wires go on the lower left side. Hopefully Country Campers Brian can fill in this detail.

I would add that pulling the fridge is not too bad of a job. I had the replacement Dometic in and out a few times until I got everything insulated, baffles fitted, etc. I built a platform on a furniture dolly to exactly the height of the fridge opening. It was relatively easy to pull the fridge out onto this dolly and then put it back.

Rob

[Yoda]

Yoda
Hi Keith,

Several years ago, I replaced my original Atwood fridge with a Dometic which looks to be very similar to what you are working with. I took some pictures which may help. I believe the sensor in the upper right corner (facing the back of the fridge) is the sensor for the fans. But maybe for more?? . . . that is heavy gauge wire for a single cooling fan . In the second picture, you can see the light weight wires and white connector going to the cooling fan.

The red wires come across the top of the OE fan and down the left side. I presume to keep then way from the hot right side. I did not take a picture of how/where these wires go on the lower left side. Hopefully Country Campers Brian can fill in this detail.

I would add that pulling the fridge is not too bad of a job. I had the replacement Dometic in and out a few times until I got everything insulated, baffles fitted, etc. I built a platform on a furniture dolly to exactly the height of the fridge opening. It was relatively easy to pull the fridge out onto this dolly and then put it back.

Rob

Thanks Rob - this is a big help. I am going to test fit the fans (hopefully this afternoon) before messing with the wire.

[Country Campers]

Yoda Cate&Rob

Here are a couple pictures.


The 2 red wires from the "thermistor?" comes to this point where 1 red wire connects to the small red wire which powers the fan. The second red wire travels down to the power input block. The black wire, ground, comes up from the power/ground block at the bottom of the fridge.


The red wire seen here is connected to the power input.

Power goes up to the "thermistor?" and when it reaches a set temp allows power down to the connection on the side to turn the fan or fans on. I would guess that you would want to connect the new fans in the same manner. Please note that the wire connected to the factory fan is pretty small.

I hope this helps and I would agree with Rob that removing the fridge is not that hard and I think it will surely make this job much easier.

Brian

[Scott'n'Wendy]

Just FYI, those temp switches fail fairly regularly. On my previous trailer I replaced it with an attic vent fan t-stat. I could then set the fans to come on at any temp I desired. About $15 at Home Depot.
Something like this. Looks like prices have jumped though
https://www.amazon.ca/AIR-VENT-58033...2628819&sr=8-3

[Yoda]

Yoda Cate&Rob

Here are a couple pictures.


The 2 red wires from the "thermistor?" comes to this point where 1 red wire connects to the small red wire which powers the fan. The second red wire travels down to the power input block. The black wire, ground, comes up from the power/ground block at the bottom of the fridge.


The red wire seen here is connected to the power input.

Power goes up to the "thermistor?" and when it reaches a set temp allows power down to the connection on the side to turn the fan or fans on. I would guess that you would want to connect the new fans in the same manner. Please note that the wire connected to the factory fan is pretty small.

I hope this helps and I would agree with Rob that removing the fridge is not that hard and I think it will surely make this job much easier.

Brian

Brian and Scott Scott'n'Wendy

Brian - this helps a lot. It's even given me a brainstorm Yes this is dangerous. I believe the red wire that ties into the power block has a fuse in the line. I like the idea of having my aux fans turn on with the stock fan. I can still us my controller, and just get power from the thermistor on the correct side. I would just need to up size the fuse properly for the new fans. The wire gauge is plenty big. Next time I am out there I will yest the thremister. I know the power at the block is hot currently even with the fridge off. It appears fan power stays on until the thermister opens when the fridge is turned off.

However if this wire is just for fan power where does the fridge get it 12V power as there is only one connection on the power block I can see and from the wiring color that power wire comes from the distribution center.

So from the thermistor on the fan power side, splice a power feed to my new PWM fan speed controller. I will have an on/of switch on the line. The controller then powers the fans and I can set the speed needed. The fans would come on when needed and be off when the fridge is off. Or I can power them separately, but then I need to turn them on manually and remember to turn them off too.

Ill do a bit of poking around and see what goes where.

I like this new plan, and it does not cost extra $$ either.

Question - if one side of the thermister is hot all the time, if I jump the thermister leads, the fan should com on to verify this wiring layout, correct?

Thanks Folks

Keith

On edit - I found the 12V wire that powers the fridge - it was buried below the fan power wire. Hare to see unless you were looking for it.

[Country Campers]

Yes, if you unplug the thermistor and connect those wires together the fan should come on. I am not sure where the fridge gets its power from , I will go out and check.

Brian

Yoda

I just went and checked, there is a second red wire attached to the connection in the second picture that goes over to the heat tube and then to the fridge control box that powers the fridge.

[Yoda]

Yes, if you unplug the thermistor and connect those wires together the fan should come on. I am not sure where the fridge gets its power from , I will go out and check.

Brian

Brian as I edited above I found it buried below the fan power wire. Were good now
Thanks

[Scott'n'Wendy]

The wire going to the fans could support about 10 fans. But I'm not sure of the current rating of the temperature switch. Probably good, but I don't know for sure.

That switch failed on me when camped in the badlands of South Dakota. Fridge warmed up. Pulled the wires off the switch and connected them with a wire nut. Fan was on 100% of the time for the rest of the vacay. (3 Weeks) but the fridge stayed cold. After that is when I swapped in the attic fan temp control.

[Yoda]

OK I have begun the actual install. First I made a mounting bracket to attach a standard fan bracket too.

I went to HD and got some 1/8 by 1.5 flat aluminum bar stock. The 1.5" dimension accommodates the fan mount you can see above. I measured 3 times, and bent and it was still a tad long so I had to rework the bends

I measured out and drilled mounting holes - a mistake. I should have fit the plane stock and noted the vent cover attachment points as some of the holes I drilled were blocked.
After several attempts I finally had the mounting access hole cut. I used a multi tool with a metal cutting blade, Its not easy. I actually cut two holes at first then had to enlarge to get my hand it to get the red wires freed. Most of the holes you see were wrong. I also discovered I miss measured the distance to the back of the fridge and the fan mounting bracket. The bracket is about 1/4 to 3/8 longer than just the fan, so I needed to pad out he mounting bracket another 3/8" used two flat bars - one 1/4 thick and the other 1/8 thick.

Flat bar padding to allow fan mount to work. I also timed the rear of the shroud backing blocks (center bottom of photo) to make room for the bars and fan mounting bracket

Fans installed and cover will close. I changed to a dual fan mount, but now I am second guessing if I should use the singles and spread the fan out about 1.5" apart. I cant go much further right due to the tube visible in the photo. The reason is the stock single fan is about 18" directly below so air would be partially blocked if theses fans were not running.. I can do a test tomorrow when I work on the wiring. Thoughts?

As you can se I freed up the stock wiring to be able to work with it. I'll get some foil tape to seal the opening around the fans. Rob @Cate&Rob, Brian Country Campers Thanks for the photos. While I did not pull the fridge I found the wiring as you both showed it. If I had pulled the fridge I probably would not have discovered the fan mount measurement issue - maybe I got lucky

Tomorrow on to the wiring. It got too hot this afternoon to do much more.

Keith

[Cate&Rob]

Hi Keith,

This setup is definitely going ot move more air than the original single fan. We have not had fridge cooling problems with the single fan. We are usually camped with the fridge side to the west (chosen whenever possible to shade the camping side in the afternoon) and the fridge fan runs all afternoon. The single (probably inexpensive) OE fan is quite audible inside the trailer. I will be interested in the noise level with these upgraded fans. Will you still run the original fan as well?

Rob