MaxAir Vents Opening, Closing, and Running Randomly

[John5five]

2020 3811ms Montana vents in the bathroom and kitchen randomly open and close with fan running. Sometimes fan comes on whether vent is open or closed.
Hit the buttons and maybe it closes or turns off the fan. Irritating.
It's winter and these things turn on and open sucking the heat right out of the box ...
Anyone have this problem and or no how to fix the problem. Don't have a month to leave it at the dealer....

 

[RMcNeal]

If memory serves, there was a feature with these Max Air fans where they would do what you described if it got too warm. We had English Bulldogs, so it was something we thought was a neat "feature". If the AC went out and it got too hot, the vent would open and help cool down the rig.
I've never had it happen, but I wonder if there's a sensor or something that has messed up? Or if there's a way to turn off that feature.

 

[Mikendebbie]

Possibilities…???
These guys bought a small voltage regulator to fix the MaxAir gremlins (bad voltage from solar or lithium batteries)…
By the way…There are LOTS of “voltage problem” videos out there.

Also I found lots of “moisture causing random action” videos. Their solution is to spray the board with a sealer to prevent moisture-caused gremlins.

In one video the person mentioned unplugging the temperature sensor while removing the board, so RMcNeal is correct about the presence of a temperature sensor. I did not search out problems with that sensor.

 

[DutchmenSport]

I don't see where you indicated your year and model for your camper. Not knowing, (if you do not have In-Command), if you have the common Dometic fan / AC / Heat controller mounted on the wall, all you need to do is simply unplug the phone jack style plug on the back of the control and see if that stops the random behavior. Simply pop the cover off, and unscrew the 2 screws. Now you can simply unplug the wires from the back.

If this stops the odd behavior, then chances are it's the wall mounted controller. If the behavior continues, then it's something going on with the fan.

If this stops the behavior, and you have a second exhaust fan controller, swap them and see if the behavior occurs on the good fan, and the bad fan now behaves as expected. Doing so will eliminate THAT is possible root cause.

If it is the wall mounted controller, then you can order a new one from Amazon. It's a simple start, and if this is the problem, then it's a simple fix.

 

[Reset19]

Can you drop the shroud and disconnect the wires