Refer fans for improved cooling...what are the best options?

[Baja_Man]

I have a Norcold N843 8cf refer with ice maker. It works well. However, when ambient temps get up to 95-105F, it struggles to stay cold. It will only cool to 46F when ambient temps are at 100F and side of RV with refer is directly facing sun.

So, since I can't control weather, and can't always predict how my RV will be parked when visiting campgrounds (facing sun), I want to ensure that my refer has all the things it needs to stay as cold as possible.

I've read about two types of fans installed to assist with cooling...

1. A fan on the evaporator (inside refer) to move the cool air around on the inside of refer and prevent frost build up on evaporator fins

2. Fans on rear on refer between the back side of refer and exterior RV side. These are used to assist with moving hot air up and out of roof vent.

The rear fans can be difficult to install if choosing to mount above coils since access is only through exterior vent lid (without removing refer).

Questions...

REAR FANS:

1. Where should rear fans be placed for most effective outcome? Above coils, on coils, below coils, etc?

2. Which fans have been proven to be most effective...computer fans, Valterra type of fan, etc?

3. Should fans be thermostatically controlled or manually with a on/off switch, or both?

4. How should these fans be wired? 12V power and ground from refer wiring OR separate 12V and ground wiring pulled from somewhere else?


INSIDE FANS:

1. should these fans be the hard wired ones that are wired to inside light OR the D battery operated type, or is there something else?

2. Are inside fans necessary or can good results be had with only the rear fans

Any other tips, suggestions or ???

Thanks!

[randallb]

On my Class A I used one of the solar powered fan units from any RV supply house with a battery operated inside the unit. After these mods I was able to decrease the temp setting by 1-1.5 numbers on the display and it did not matter whether the reefer was on the sunny or shady side of the RV. Solar; no muss, no fuss. This performance improvement was monitored during a 9 month trip and I never worried about reefer performance again. Do not over think this. RV reefers have been installed loose since their inception.

[wa8yxm]

For improved cooling I use 4 computer type fans. all 12 volt, all run on the LIGHT circuit of the fridge (Before the door switch) so they run whenever it's on.. With temps pushing 100 outside (hit a time or two) Ice Cream remains frozen. Milk remains cold.

Two fans inside, two out.. Source on most of them is All Electronics (A surplus store) so I have to wire them up.

[kenparsons]

I have a 02 Monaco Dip with a norcold n843. I have 120mm computer fans coming for installing "inside" the refer box. Where do I get 12v power? I am also going to install fan on the outside coils but that isn't a problem finding 12v there. Ken Parsons

[denk]

austinjenna wrote:
I have 2 computer fans at the top of the refer vent to suck air out and 2 at the bottom to blow air in.

How did you connect the power to the fans? and what device turns them on?

[austinjenna]

I have 2 computer fans at the top of the refer vent to suck air out and 2 at the bottom to blow air in.

[GACamper]

Our frig has two fans on the backside. I did upgrade one fan to a larger CFM. I took one fan out and replaced with with Model #AFC1212D. Frig works a lot better since I did that.

[GordonThree]

BoonHauler wrote:


Thanks for the link, only bummer is their controllers require a 5vdc source as well as 12vdc.....:(

That's no problem... This little guy will turn 12v into 5v very simply. The humble and ancient 7805 voltage regulator.

You'll need two of these, one on the input, one on the output.

Connections are as follows:

[GordonThree]

BoonHauler wrote:

Gordon:

Where did you get your controller? .... No speed control is not an issue for me.

Thanks

I designed and built it myself. You can get my bare circuit board here: clicky ... I'm not selling them, just sharing the blueprint.

If you're experienced with microelectronics, you can build three of them for under $30. They are programmed like an "Arduino", with a few modifications to the programming environment.

[BoonHauler]

TechWriter wrote:

GordonThree wrote:

BoonHauler wrote:

TechWriter wrote:

BoonHauler wrote:
Anyone using a thermostatically controlled switch to turn the fan/s on and off?

Any links? How are you controlling the fans/s?

www.coolerguys.com

I don't think the Cooler Guys have any control devices. I been through their website and ordered my fans from them.

I've got an email into them just to make sure.

Here they are, if you like that vendor...

http://www.coolerguys.com/fanc.html

And here . . . and I like this vendor.

Tech:

Thanks for the link, only bummer is their controllers require a 5vdc source as well as 12vdc.....:(

[BoonHauler]

GordonThree wrote:

BoonHauler wrote:

So with your set-up do you have an upper and lower limit (set point or do you have a simple on above set point, off below set point?

I'd have to think the later would be susceptible to cycling.

Yes, two set points, one for on, one for off.

I think most thermostatic devices, electronic or mechanical will have some degree of hysteresis, to avoid too-frequent cycling. Where it's adjustable or not is what adds cost 🙂

One limitation of my little module is it lacks speed control (it was really designed to control other loads). So the fans are full on or full off. I'll try to include that ability in the next revision.

Gordon:

Where did you get your controller? .... No speed control is not an issue for me.

Thanks

[TechWriter]

GordonThree wrote:

BoonHauler wrote:

TechWriter wrote:

BoonHauler wrote:
Anyone using a thermostatically controlled switch to turn the fan/s on and off?

Any links? How are you controlling the fans/s?

www.coolerguys.com

I don't think the Cooler Guys have any control devices. I been through their website and ordered my fans from them.

I've got an email into them just to make sure.

Here they are, if you like that vendor...

http://www.coolerguys.com/fanc.html

And here . . . and I like this vendor.

[GordonThree]

BoonHauler wrote:

So with your set-up do you have an upper and lower limit (set point or do you have a simple on above set point, off below set point?

I'd have to think the later would be susceptible to cycling.

Yes, two set points, one for on, one for off.

I think most thermostatic devices, electronic or mechanical will have some degree of hysteresis, to avoid too-frequent cycling. Where it's adjustable or not is what adds cost 🙂

One limitation of my little module is it lacks speed control (it was really designed to control other loads). So the fans are full on or full off. I'll try to include that ability in the next revision.

[GordonThree]

BoonHauler wrote:

TechWriter wrote:

BoonHauler wrote:
Anyone using a thermostatically controlled switch to turn the fan/s on and off?

Any links? How are you controlling the fans/s?

www.coolerguys.com

I don't think the Cooler Guys have any control devices. I been through their website and ordered my fans from them.

I've got an email into them just to make sure.

Here they are, if you like that vendor...

http://www.coolerguys.com/fanc.html

[BoonHauler]

TechWriter wrote:

BoonHauler wrote:
Anyone using a thermostatically controlled switch to turn the fan/s on and off?

Any links? How are you controlling the fans/s?

www.coolerguys.com

I don't think the Cooler Guys have any control devices. I been through their website and ordered my fans from them.

I've got an email into them just to make sure.