TheSamba.com :: View topic - How-To: Adding External and Internal Fans to Your Dometic Fridge

Wed Apr 10, 2019 10:37 am

Others have added fans to their Dometic Refrigerators, this is my implementation.

I've tried to include where I tapped and how I ran wires. Other how to's I found didn't seem to cover that part real clearly.

Hope this helps someone out in the future.

What you'll need:
1 or 2 4" 12V computer fans.
1 2" 12v computer fan
Standard automotive wire. If you can get yellow and blue it will keep the wire colors same as the fridge wiring. I used red and blue because that's what I had.
Spade connectors, wire splicers zip ties and crimpers.
1 standard accessory toggle switch. Get an led light for power savings.
Something to make a fan bracket with. I used muffler repair sheet metal. It's easy to cut with a scissors, easy to form and strong enough for a fan bracket.
Drill and bits
Self tapping sheet metal screws
12v 1amp trickle charger and small alligator clamps (for testing.)

Note 1: On the fridge, yellow wire is 12v positive from the camper and blue is 12v ground to the camper.
Note 2: You could be on the house or starting 12v battery. It depends on your van setup. This is important because if you splice in prior to the thermo sensor, and leave the switch for the fan in the on position with the van off or without charging you may drain your battery over time. This includes when you run the fridge on AC shore power! You've been warned.
Note 3: Leave enough extra wiring for future adjustments. I don't have a house battery on mine "yet." So I left plenty of wire to the switch to be able to splice or wire into a switch panel in the future.

Prep:
Remove the Dometic fridge. https://youtu.be/re2VMY3nIcU?t=9
Clean up any debris, cobwebs, mouse nests, dust bunnies from the fridge and the inside of the cabinets. Look for rust and general condition. You may want to clean your propane burn chamber.

Rear fan addition
Test your existing fan by connecting 12v power to circuit.
Easiest to use a 1 amp battery charger and connect with smaller alligator clips
+ to the yellow wire on "out" side of the thermo sensor.
- to the blue wire connector next to the thermo sensor.

Fan should run vibration free and actually moves a decent amount of air. Clean any dust from the fan blades, replace if necessary.

Mount Fan(s)
Any 4" 12v computer fan. I had a couple left over from old computers in the basement.

I made a quick bracket out of some muffler repair sheet metal I had laying around. You may be able to screw the fan directly to the back of the fridge with self tapping screws as well. Just depends on the fan shroud.

Wire Fan
Red wire of the fan gets tapped into the yellow wire below the thermo sensor.
Black wire of the fan gets tapped into the blue wire below the connector.
Something I did was get a computer connector and use it so I had a quick disconnect for the fan. The fan computer wiring I used also had another connector already attached, so I can quickly add another fan in the future if I want.

That's it, your done. The new fan should kick on when the thermo sensor trips.
To test, just connect up your alligator clips like before. + below the sensor, - on the blue wire connector. Both fans should now run.

Adding fan to the cooling sink inside.
Drill Holes:
You will need to drill 3 holes. 2 in the back of the metal cooling sink, 1 in the back or side of the fridge for the wire to go though.
Be especially careful drilling the hole though the refrigerator. It's hard to estimate where exactly it's going to come out. I drilled from the inside upper right and it came out as illustrated in the pics below.

Mount the Fan:
Run the wire though the hole and then zip tie the 2" fan to the top of the heat sink. I only used 2 zipties, holds just fine.
Use some silicone to seal up the holes, inside and out.

Switch location:
Find a spot you want to mount the switch. Originally I drilled a hole in the fridge's plastic face to the right of the Dometic logo. Little did I realize that the white cabinet face would cover this up. Dolt...I'll find another spot, I think I'll put it up by the stove controls or electrical indicators.

Fridge Wiring to switch wiring:
Spice into the yellow wire PRIOR to the thermo sensor. This runs to the Positive terminal of the rocker switch.
Splice into the blue wire or re-use the spice from the rear fan. This runs to the Neg. side of the rocker switch.

Fan to switch wiring:
Wire the red wire from the 2" fan to the ACC (accessory/load) terminal on the switch.
Wire the black wire from the 2" fan to the Neg. terminal on the switch.

Test by connecting your positive 12v supply to the input / top of the thermo sensor and negative to the blue wire connector again.
Flip the switch and you should have a running fan and led indicator on the switch if your switch is so equipped.

Reinstall the fridge is the reverse of removal. Best to get your electrical plugged in and test the switch quick before installing any screws, propane etc.

Wed Apr 10, 2019 10:47 am

Great write up! Replacing the stock fan did wonders for ours - next to add additional fin cooling. Thanks for the great step by step!

Wed Apr 10, 2019 11:25 am

This project is on my list and you've made it so much easier. Thanks a lot !

Regarding the cooling sink fan inside the fridge, are there switches that, when turned on, turn the fan on say 5 minutes every 20 minutes? or 2 minutes every 10 minutes ? That would be ideal.

Wed Apr 10, 2019 11:27 am

VicVan wrote: This project is on my list and you've made it so much easier. Thanks a lot !

Regarding the cooling sink fan inside the fridge, are there switches that, when turned on, turn the fan on say 5 minutes every 20 minutes? or 2 minutes every 10 minutes ? That would be ideal.

I'm betting you could find a switch like that. If you do, LMK because I may be inclined to buy it since I have to move my switch anyway. I would imagine the wiring would be the same.

Wed Jan 24, 2024 5:00 pm

I think my heat sensor is bad or going bad. The fan is always on and is hooked up to a switch to turn off. I guess that's better than always off...

Wed Jan 24, 2024 6:25 pm

What's the part number of that thermo switch you pointed at? What's the heat sensor called? It's called the thermostat.

Wed Jan 24, 2024 8:10 pm

Wow, that is one detailed write up, with great photos. I'd concur with other posters that it does improve the efficiency of the Dometic.

Too bad that post hadn't been available when I did similar work. Here's my take on this mod.
http://www.griffco.ca/VW/vwfridgemods.htm

It may be of some slight help to anyone else tackling this improvement.

Note that the first wiring diagram under the "Now The Cooling Fans" is as shown in wiring diagrams from VW, Bentley et al. However the third panel in that area is the correct version.

Thu Jan 25, 2024 9:34 am

spitsnrovers, that's what I call serious modifications done to perfection.