In my Sanibel 3500, the bathroom "exhaust fan" in the roof is the Ventline 2094 unit. The ceiling in the bathroom is at about 7 feet and my vertically-challenged wife can't reach the "crank-open" knob or the switch to turn the fan on. Putting a step-stool in these small bathrooms isn't an option I'd entertain, and I was getting very tired of having to turn on the vent for her every time she wanted it on.
In the kitchen area (high ceiling), PrimeTime installs the 2119 unit, which is opened and turned on/off remotely, so I knew what was possible, but didn't want to break the seals on my roof in install a different unit, and the two looked very similar. Ventline couldn't tell me if it was possible to convert one to the other, so I found out for myself that yes, it's actually very easy to do.
The original unit looks like this (with the ceiling garnish removed):
What you need is just a few parts which I found for a good price at Etrailer.com. First, you need the Gear Motor
that is used to open and close the dome. Note that this includes the motor mounting bracket that you need. (It doesn't include the screw that they show in the picture.) Then you need the gear
that the motor meshes with. This gear replaces the knob that was present on the original unit. This also includes a metal spacer to keep the motor the right distance from the crank. (This one does include the screw that you need to attach the gear, which isn't shown in the picture.) That's all you need to make the modifications to the vent, but just to keep this all in one place, you also need the remote switches
that you use to control the vent. This switch assembly comes in either black background with white lettering or white background with black lettering. Total cost at this time: $46 plus tax/shipping, etc. (Note that you would have had to buy that switch assembly even if you'd replaced the vent unit instead of modifying the one you had.)
To perform the conversion you'll want to consult the parts diagram
that Ventline makes available. The eTrailer.com parts diagram pictures are also useful. The numbers I'll reference here are from the "automated" parts list (2119). Remove the "ceiling garnish". Use the knob to open the vent about half-way and then the remove that knob. The "screen base" (17) just clicks into some tabs on the aluminum cross-piece. Push the attachment points in a bit and it will come right out. Next remove the "crank assembly" (6) by taking out the 2 screws (8). The attachment to the "dome" will just slide right out, and turn the crank assembly a bit sideways to get it thru the aluminum cross-piece.
The crank assembly fits below the matching screw holes in the new motor bracket you've purchased. Also, that metal spacer (9) that comes with the new gear goes over the "crank shaft" where the knob used to attach. (Temporarily remove one of the motor mount screws (13) to attach that spacer to the motor bracket.) Then just re-install the "crank assembly", now with the motor and motor bracket sitting next to it. Those original two screws (8) hold the whole assembly in place. Put the new gear (10) onto the crank shaft where the knob used to be. The finished assembly looks like this:
What I found, after tightening it all down (can't tell before then) is that the two gears were meshing too tightly. I found that rotating the motor on the bracket about 1/3 turn eliminated the pressure. (In other words, you need to change which motor holes line up with which holes in the motor mounting bracket.) (The description of the bracket on eTrailer.com suggests this purpose for the bracket which is how I knew to try this.)
As I suggest in the picture above, don't route the wires through that hole in the cross-piece unless you like having to do things over again.
Put a little bit of grease on the two gears and then re-assembly of the remaining parts is just the opposite of taking it apart.
Now for the wiring. There are two motors on your completed work piece with two wires each. There is no "sharable common" on these connections so you need to run four wires from the fan assembly to where you want to install the switch. At the switch, in addition to those four wires, you'll need 12v hot and common wires. (You already had that 12v hot and common at the fan originally, so you can use this as the source voltage if needed.) Wiring up the switch is straight-forward but unique to your particular RV of course. Here's the picture of my completed switch installation: