Fridge Vent Fan

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johnandrew70

johnandrew70

Apr 28, 2011
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This weekend i am going to install a fan in the fridge vent, My question is can i take a 12v feed from the back of the fridge somewhere and if so what colour are the wires??

This is what i am installing into the vent aperture 2x120mm silent computer fans connected to a temperature controlled fan driver.

20140812_174212_zps0e4bb1c8.jpg


Then the fan driver will be switched by replacing the single awning light switch with this double switch.

20140812_174717_zps9bb0d30e.jpg


All i need to know is the wire colours for the fridge light and lcd display cable.
 
johnandrew70

johnandrew70

Apr 28, 2011
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Hi Sprocket
I am hoping that my fans will do the same job, the temperature controlled device works really well home here on a 12v battery, the fans spin at a slowish speed and as it gets hotter the fans speed up. that was about £9 on ebay the fans were about £8 they are silent running, and the double switch was £4 the aluminium was £3.

I am using the fan controller as i want to just leave it and let the temperature control it, not sure where to place the sensor though.
 
M

Mike_S

Dec 9, 2009
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Hi John
The following is the text of an article I submitted to a "well known caravanning magazine". Hopefully you may find it useful
Mike
Fitting a Fridge Cooling Fan

We can recommend Italy as a holiday destination - beautiful scenery, good food and wine, etc! The down side is the long tow and the heat once there. We can cope with the heat but the caravan fridge struggled to keep its contents cool.

On our return, I investigated fridge cooling fans. Thermostatically controlled fan kits are available for £31 to £46. I felt that I could find a cheaper but equally effective alternative. Thermostatic control I could do without - I know when its hot!

The "kit" I got together is shown in Picture 1 :-
Two 80mm 12 volt fans from Maplin (RG03D - £4-99 each)
A suitable switch and indicator light - I had these already but an illuminated rocker switch can be bought from Maplin for about £2.
About 2m of twin flex, Araldite or similar adhesive, a couple of scotchlock connectors and a couple of spade connectors - again these I had already.

First, a word of caution. This job does not involve the gas or mains electric operation of the fridge: 12 volts won't kill you BUT if you don't know what you're doing you could still do a lot of damage to your caravan. If you don't feel fully competent to tackle this job then don't - or leave it to someone who is. I would also recommend that you disconnect the caravan battery and mains hook-up whilst doing this job just to avoid any chance of short circuits.

The first step is to remove the upper and lower ventilator grills from your caravan - ours is a Bailey Senator (2009) fitted with a Dometic fridge. This is done by sliding the latch at the left hand end of each grill upwards. The grill can then be (carefully) levered out from the left hand end. See picture 2.

The two fans are glued to the inside of the upper ventilator grill and weighted down while the adhesive sets. Picture 3. Thoroughly clean the grill first to ensure good adhesion.

The fans were then wired together and tested to check that the airflow was in the right direction ie blowing out through the grill - if not, swap the connections round. When wired in parallel the fans worked at full speed but I thought were a bit loud so I rewired them in series. The fans ran more slowly but still generated enough airflow and were significantly quieter. The fans are coupled using two pairs of spade connectors to allow the ventilator grill and fans to be removed. Picture 4.

The lower ventilator grill, once removed, gives access to the wires connected to the fridge. A pair of black wires are tagged "nur 12v" (only 12v). One black wire has two thick conductors, the other black wire has two thinner conductors. All four conductors meet at a four-way connector. See picture 5.
The power for the fans must be taken from the supply side of the connector so the fridge may be removed for maintenance if required.
The two thick conductors (orange and black) power the fridge when the car and caravan are coupled up and the car's engine is running. The two thinner conductors (green and white) provide 12v to the fridge for the internal light and are connected through to the caravan's fuse box. It is this pair of wires that will power the cooling fan using scotchlock connectors. See picture 6.

The fans, switch and indicator light are wired as shown in the diagram below.

Routing the supply flex to the switch (and indicator light) and then back to the fans will vary depending on the layout of your caravan and where you choose to mount the switch - mine is mounted on a upper panel inside a kitchen cupboard. Picture 7.
Make sure the flex is away from any heat sources and can't chafe against any sharp edges.
Replace the ventilator grills. Job done!

A return visit to Italy last summer proved their effectiveness!
 
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chrisbee1

Dec 11, 2009
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Mike_S said:
Hi John

The "kit" I got together is shown in Picture 1 :-
Two 80mm 12 volt fans from Maplin (RG03D - £4-99 each)
A suitable switch and indicator light - I had these already but an illuminated rocker switch can be bought from Maplin for about £2.
About 2m of twin flex, Araldite or similar adhesive, a couple of scotchlock connectors and a couple of spade connectors - again these I had already.
Click to expand...

Aghhh, Scotchlocks, the scourge of auto electricians everywhere :angry:
 
M

Mike_S

Dec 9, 2009
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Actually, I agree about scotch locks! I wouldn't use them when dealing with relatively high current devices like lights, etc. but these fans are only a couple of watts each and perhaps, more importantly, in this application they are easily accessible should there be a problem and to date, the setup has worked perfectly.
Mike
 
Gafferbill

Gafferbill

Jul 15, 2008
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Hi Mike_S................I am wanting to understand the science involved behind fitting a fan to the upper vent of a caravan refrigerator.

I would be grateful if you could tell me if you caravan in hot climates with an awning attached to your caravan on the refrigerator vent side?
I have this theory that it is the higher ambient air temperature present in an awning that is affecting caravan absorption refrigerator efficiency so that a fan is required.

........as an aside I have found that almost completely restricting the air flow through the vents greatly improves the refrigerator efficiency whilst towing and using 12 volts!
 
R

Robtel

Aug 4, 2005
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johnandrew70 said:
All i need to know is the wire colours for the fridge light and lcd display cable.
Click to expand...

In my current and last van I installed the double fan set up behind the top vent, or more accurately, an electrician friend did most of it. On both occasions we found the easiest way was to run cable under seating and connect closer to the battery as it was clearer which cables were which.
Can recommend installing the fans whichever way you connect, does make a difference.
Rob
 
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colin-yorkshire

Mar 13, 2007
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Gafferbill said:
........as an aside I have found that almost completely restricting the air flow through the vents greatly improves the refrigerator efficiency whilst towing and using 12 volts!
Click to expand...
hi Bill,
I am sure I read in my caravan documentation somewhere it recommends fitting the winter covers while towing.
 
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RogerL

Nov 6, 2005
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colin-yorkshire said:
Gafferbill said:
........as an aside I have found that almost completely restricting the air flow through the vents greatly improves the refrigerator efficiency whilst towing and using 12 volts!
Click to expand...
hi Bill,
I am sure I read in my caravan documentation somewhere it recommends fitting the winter covers while towing.
Click to expand...

A couple of weeks ago, during the hot weather, I commented to a nearby caravanner that he'd left his winter covers on but he was sure the fridge was working just fine!
 
M

Mike_S

Dec 9, 2009
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Hi Gafferbill
My caravan (Bailey S6 Senator California) has the fridge on the offside so its vents are never in an awning.
Forgive me if the following sounds like grandmothers and eggs!
For a fridge to work efficiently the heat abstracted from the fridge cabinet (and thus cooling it) by the evaporator - silver finned bit (I think!) has to be dissipated by the black finned condenser at the back. In doing so the condenser gets warm and is normally air cooled by natural convection currents through the lower and upper grills in the caravan wall. If the ambient temperature is on the high side (and nearer to the temp of the condenser), natural convection will be reduced and the cooling will be less effective. Fitting a fan merely assists the natural convection and so maintains cooling efficiency which is why the fan(s) need only to be low power.

Re your aside about restricting airflow through the vents improving efficiency whilst towing ....
I got out my Dometic handbook and looked up winter covers. On page 25 it says "When the outside temperature falls below 8C the winter cover should be fitted. This protects the unit from excessively cold air which could have adverse effects on the performance of the unit.
Maybe, whilst towing, there is excessive cooling and the unit does not work as efficiently as it should.
We're off to Twinwood next week so I'll try towing with the covers on and see if my beer arrives there well cooled!
Mike
 
Gafferbill

Gafferbill

Jul 15, 2008
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Thanks for that much appreciated.

I have not fitted fridge fans even though I often caravan in temperatures over 30deg C.
My solution to the problem is to take an ordinary domestic 1.5 cubic feet table top freezer.
This has no problem in pre cooling food and drink before putting into the caravan fridge.
This greatly helps out the caravan fridge which can then manage to keep everything cool in such conditions.
It can of course also store frozen food and make plenty of ice for cool drinks.
It cost £99.00 and is10 years old and has not suffered any ill effects caused by transportation.

Just a different approach..........I am not knocking fridge fans :)
 
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DeliDave_

Mar 2, 2010
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Mike _S, Thanks for the photos I might get the chance to see it in action as we are at Twinwood Thursday too,hoping for some sunny weather to go with the music :cheer:
 
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RogerL

Nov 6, 2005
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Gafferbill said:
Thanks for that much appreciated.

I have not fitted fridge fans even though I often caravan in temperatures over 30deg C.
My solution to the problem is to take an ordinary domestic 1.5 cubic feet table top freezer.
This has no problem in pre cooling food and drink before putting into the caravan fridge.
This greatly helps out the caravan fridge which can then manage to keep everything cool in such conditions.
It can of course also store frozen food and make plenty of ice for cool drinks.
It cost £99.00 and is10 years old and has not suffered any ill effects caused by transportation.

Just a different approach..........I am not knocking fridge fans :)
Click to expand...
At the risk of thread drift - do you run the tabletop freezer through an inverter during your journey to warmer climes or do you only start it up when you get to site?
 
Gafferbill

Gafferbill

Jul 15, 2008
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RogerL.......I only switch it on whilst on a site with EHU.
It is only rated at 70 watts but the peak start up current is too much for my 600watt inverter.
I make do with the caravan refrigerator/ freezer on the journey which always has winter vents fitted when towing.
 
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