Variable Speed (PWM) Ceiling Fan Mod == 10 Bucks

Freespirit

BrianZ,  thank you for taking the time to post your pictures of the PWM Controller install. My wife and I followed your picture instructions to the “T” and everything went back in place perfectly and worked as expected the first time. No issues at all!!  We can now leave our portable fan home and use that space for something else. 

BrianZ

You're welcome, @Freespirit.  Glad to hear it worked for you the first time - that's great!
@MuttonChops found a great application for the PWM controller.  It has really helped us sleep without excessive fan noise & also conserve battery power when camping without hookups.

Slackers

Jumping in late, but I just completed this mod.  It was as simple as swapping out the 3-speed switch for the variable speed rheostat provided by @Lloyd above.  The existing connectors aren't an exact match with the new part but I made them work.  Ultimately I'll have to replace the connectors or apply a couple dabs of solder for connections that will hold up in the long run.

JeffroNC

I added one to the bathroom fan in our 400. On low speed you can barely hear the fan. I can run it in the rain as well. I prop the door open with a pool noodle. 

I was all set to swap out our fan but I’m happy as is. 

Maxcamp

Thanks to all the prior wizards for their trials and posts on making the speed controller retrofit a success.
Who else has had the fan cover plastic tabs fail?

While adding a fan hood to our 2021 TAB 320, I found a piece of black plastic atop the fan screen.  Turns out the lifting mechanism attaches to the fan cover via two extruded plastic 'clip angles' which cracked where the sheetmetal screws go into them.  Have not read about this happening to others, we travelled on very bumpy highways with the lid socked down.  
Upgrading to variable speed control and disassembly elicited the second clip angle was also broken.


Pic 1. Cut the clip angle remnants off with a dremel wheel and fabricated an aluminum angle to mount he lifting mechanism to.  SS #12 x 1/2 sheetmetal screws through fan lid, did not want to remove the added hood to through-bolt which would be better.  Buttered the holes with silicone caulk before assembly.



2. removed four-position original fan switch, used 1/8 drillbit to slot edge for metal tab on potentiometer (speed control knob) so it does not swivel after mounting.  Mounted potentiometer here.  Peeled and scraped off 0123 label and created a tapered arrow label in its stead.


3. After experimenting with speed controller (printed circuit board) locations, determined the only feasible spot is angled atop the potentiometer (below photo 2 above) as others have done.  Made plywood support for it to anchor to.  Epoxied plywood to plastic fan cowling.  Covered potentiometer with stickyback epdm pipe insulation to prevent circuit board shorting.



4. Used angle grinder to remove corner of outer heat sink, to clear fan cowling. Careful not to overheat board from the grinding heat.  Test fit into cowling and test fit cowling into fan opening.


5. Hot melt glued controller board in place.


6. Wired it up with 14ga stranded, see PDF.  You need both fullsize and half-width female spade connectors, insulated or heat-shrunk.  Cut down several zip-tie adhesive-backed mounts to corral wires.


7. Final install.


8. PDF wiring diagram.

Maxcamp

15 month followup.  Had to replace fan motor due to whining. (The fan motor not the occupants.)  Less than 1000 hours on it.  Unhappy that I had to swap it out so soon.  Also the injection molded fan rotor assembly exhibits stress cracks around the shaft opening.

New fan motor, mounting arm, and fan from Amazon.  DOMETIC-K8017-00-Blade-Motor-Assembly/dp/B01N1MK7T9 for $57.
However the shaft has significant runout and the rotor wobbles... it will not last!  Not as visible during preinstallation test off 12v power center.

Pulled 12v fuse during work.  
Pulled interior screen, unscrewed and pulled fan blade from below.  


Must remove added fan hood, unscrew raising arm, and access from top of camper, to access the four fan arm screws.


Pressure switch interrupts power when fan lid is down.  Black  lead of replacement fan has ring connector, must unscrew pressure switch from above camper to replace this lead.   (You can pull out this banana plug from below rather than chopping off and replacing crimped connector to in/out selector, as I did.)

We run fan outgoing  at low speed 100% of time when occupying camper.  Reverse to inflow during showers and heating water on stove.  
Just added a cooking exhaust portable 12v fan below stove wall cab as well.