Refer Fan Installation…

The refer fan I’d installed in the Bounder had worked so well to keep frost down, that I knew I wanted one in the Journey’s refer. There’s just so many advantages that it’s silly to do without one. There’s a few differences between the refers, my new one is a Norcold, so I’ll show and discuss those here. But first, read this article to get the background and reasoning behind installing a fan in a RV’s refer…

Link to the article: Refer Fan DIY Installation in a Dometic refer.

This article will deal with the installation of a fan in a Norcold refer:

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The first thing about the Norcold that’s a bit different from the Dometic I had in the Bounder is that I couldn’t find the door switch for the light. It must be magnetic or something and hidden under a cover somewhere. It was obvious in the Dometic. Well, never mind, I’m not going to remove trim pieces just to find it in the Norcold so I’ll just install the fan and see what happens. What I did was pop the plastic crystal cover off the bulb and using a DVM, measured the voltage on each end of the 12V incandescent bulb to a known ground. I found that one end of the bulb has a constant 12V, the other end is switched by the door opening or closing. Just what I need. It has 12V available when the door is closed, and ground when the door is open, which turns on the light. Since it’s incandescent, that means I can use the same method to wire in the fan that I did in the Bounder without worry that I’m drawing too much current for the size (gage) of the wiring. One end of the fan is wired to the switched end of the bulb, the other end to a ground somewhere inside the refer. When the door is opened, the switch closes…that applies a ground to the bulb and it lights, but it also removes voltage from the fan so it stops spinning. The below schematic shows the condition when the door is open…the lamp is on, and the fan is off. When the door is closed, that opens the switch so the light goes out, but now the fan runs because it’s supplied by the small amount of current going through the bulb. It’s enough to run the fan at near full speed, but not enough to do more than cause the lamp to glow dimly, producing very little heat. Now newer RV refers may soon be offered with white LED bulbs. This uses as much as 10X LESS current as an incandescent bulb so the wiring can be smaller, and the switch less robust. And the big issue is that there won’t be enough current running through the LED bulb to power the fan when the door is closed. I’m working on an idea for that case but for now, if your refer bulb is LED, this method won’t work. Keep that in mind. But you could probably change any standard LED base bulb to an incandescent…if the wiring is heavy enough. 18 GA should be fine.

Refer Fan

The only thing necessary to add this fan to this model N842IM Norcold, and likely many others of their models, is to wire the fan as shown in the above schematic. The only issues are to find a convenient place to wire it in, and to find a place to mount it. The model 842 turned out to be easy.

It’s a little difficult to see in this picture but there are 1/4″ connectors in this lamp assembly, and for testing, I just used some clip leads to connect the leads of the fan to both the metal of the cooling fins (which I’d measured and found to be grounded to the RV frame ground) and to the appropriate lead in the light assembly. The door has a 1/2″ or so gap when it’s closed enough that the light goes out, or the fan comes on, so that’s what I did to verify things, almost closed it, and looked.

Worked fine, and allowed for discovering which lead behaved the way I needed, so I chose a spot to mount the fan, then cut the lead to the bulb, in this case the lead at the rear of the assembly was the switched wire, and wire nutted it to the fan wire. The ground lead of the fan, I soldered on a grounding clip that electricians use to attach a ground wire to a metal wire box and pushed that onto one of the cooling fins, making a tight connection to that grounded metal. You can see it to the left of center clipped onto a fin.

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Readers can see I only used one fan. I used double sided tape and just stuck it to the ceiling inside the refer a couple inches from the cooling fins. I put it on the right side because that’s where the cooling juices are the strongest in this refer. It’s high enough that a loaf of bread fits under it.  And once everything was all trimmed out nicely, it’s looking good.

So far, after 3 months of operation, the fan is doing a great job of keeping frost from building up on the fins. I didn’t know if one fan would do the job when I installed it, but it seems to be working fine, so I’ll just stick with one fan. Even now when we’ve been having wet weather and 60% humidity the fins are still mostly frost free.

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This installation was easier than with the Dometic refer and only took a few minutes of work so I highly recommend you DIY’ers give it a try.

Update – Sept. ’17

Still works good after one full year plus a couple months over two summers. I’ve never had to defrost the refer portion since I installed the fan. I did have to defrost the freezer compartment once but that only took a total of 30 minutes using a heat gun. A hair dryer would have worked too.

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