bathroom fan issue

[LaMonte Monnell]

My bathroom fan has decided to cause issues. With the switch on automatic and everything else off the knob keeps turning and doesnt stop, unless you shut the fan control switch off. In manual mode it doesn't raise the cover, the knob just spins freely.
Not sure where to begin'


Is Dometic the owner of fantastic fan now?

[Frank Bergamo]

LaMonte, if you push up on the knob, it will engage the gear motor assembly. It then should snug down the lid and stop running. Hope this helps.

[LaMonte Monnell]

I tried to do that but mine isnt like that I dont think.  It has a switch to set to manual or auto.....in manual it isnt doing anything at all. The knob to raise the lid just turns and does nothing.

[Don and Kathy DuCharme]

LaMonte, if it is like ours there is a small coupling between the motor and the lift rod. We have had two of ours strip in this coupling and the result is as you describe. I don't know of a fix other than replacing the motor assembly. I have been able to do a temporary fix with JB weld, but not sure it is a good idea, since it may be difficult to remove if necessary.

[Joel Ashley]

Your lift arm and/or the drive gear has worn/stripped.  I replaced a motor and gear some years ago, and not long ago the lift arm. There are previous threads here about the topic. 

There are useful YouTube videos also, e.g. look up  “RV DIY - Fantastic Vent Opener Repair”.  And “fantastic vent lid would not closed , vent lift arm replacement”.  I don’t necessarily agree with those examples’ methodology, but there are other videos that may be more spot-on with your particular model and issue. 

And yes, Dometic bought Fantastic Fan awhile back.   https://www.dometic.com/en-us/us/support

Joel

[LaMonte Monnell]

UPDATE:The motor gear is ok but the lift arm gear is stripped out badly. Its the original fan from June of 2000 so no complaints from me. Everything else works so I ordered a new lift arm to be delivered tomorrow. Thanks to everyone for the help once again, I surely appreciate it. At least now I know how these work, kind of!

[Joel Ashley]

Be sure you ordered the correct arm;  there’s a slight difference in some.  And the last one I ordered had been updated, doing away with a troublesome stop pin in favor of a nub as part of the arm body.

Joel

[LaMonte Monnell]

I got the new lift arm installed but the spline gear in the lift motor is stripped  ..trying now to see if I can even get a replacement lift motor, Dometic states they no longer make the one I have.
i may have to bite the bullet and replace the whole unit, it will be fun removing the sealant on the roof first to get the old one off.

[Gerald Farris]

LaMonte,
All of the parts for your Fantastic Fan that you would need to replace are serviceable from inside the coach, even up to and including an upgrade kit. So nothing will need to be done on the roof. However, if you need to replace the dome, that requires removing a couple of screws on the roof, but no sealant work.

Gerald

[LaMonte Monnell]

thanks Gerald