Adding a Roof Vent Fan in a vent where there is none

If the wiring diagram shows the vents as prewired, you have it made.

If you can't go through the ceiling, think about ways you could go on the ceiling and hide the wires with trim.

As others have said, the wiring is variable by mfgr. I would contact them and give them the model and VIN.

You will not have to remove roof or ceiling. Do a YouTube search on "removing rv vent".

I would install a Fantastic Fan. I would also add a vent cover at the same time.

Like others said, if no pre-wire, look for a ceiling light within striking distance of your fish tape. Simple to do in most cases because there is usually a light you can tap into not far from a roof vent or in the same room as the vent.

AlwaysDreaming wrote:

There is a 12V light near (30 inches) the vent which is not on a switch (push button on the light), how would I splice into it? How do these lights detach?

Is there special tools or techniques to snake wires in the RV ceilings? I assume there is a “space” between the outside roof and the inside roof? Do you have to take the inside roof off to do the wiring?

Like people said, remove the trim and look for wires. They don't always pre-wire it for fans but you might see the lights wires nearby. I didn't see any conduits or hidden boxes in my Thor Dutchmen, only wire nuts. If wires are too far, try pulling them close enough to work - carefully, without ripping them off the wire nuts.

Lights are attached with a few tapping screws in ceiling plywood, take the lens off and you will see. In the worst case, and if the trailer is old enough to not worry about appearances, just run the wire from lights to fan along the ceiling on the outside, i.e. not hidden in the ceiling, paint it white and let it be.

In my experience with TC's, TT's and a class C, most vents have been pre wired whether they had a fan or not from the factory. Take the trim off and dig around in the insulation.

My oem used same wiring harness for many different models. You could remove vent "garnish" and lift up roof trim stapled down and take a look for 12 volt wires. If so go from there. I used a unfolded coat hanger to fish with.

If the light has a button on it then you have constant 12v so no problem there but if you need to know how the light detaches then I would guess your in over your head. Probably cheaper for someone to do it than fix it.

Many of the lights are wired with wire nuts. Super easy to wire in if you can pull the shroud around the vent and drop the light- likely there is room between the ceiling and the roof, like in our camper.

I just did one this summer.

I recommend replacing your light bulbs with LEDs. Sometimes more than one light is on a circuit, so you want to do all the lights on that circuit at a minimum (should do them all, IMHO).

In our camper, that gave me comfort that we wouldn't overload the wiring or circuit when we added the very low amp usage- Fantastic Fan.

I did have to order a new inside shroud as our vent had rounded inside corners and the Fantastic Fan had square corners.

Just be careful when setting your fan in place that it is level and not twisted or bound...or you'll get vibration. The screen that mounts over the fan and opening is more sensitive to any twisting as it has little structure- only the plastic frame.

That's it. Pretty simple, if you are using a Fantastic fan ;)

Good luck!

I have done a ton of this kind of work and the feasibility really depends on how the rig is insulated, where things like ceiling ducts are and many other factors.
If your not comfortable with this kind of mod, hire a pro.