Ventline Northern Breeze Fan has a mind of it's own

I have a 26' 2003 Alumascape trailer with a Northern Breeze Ventine fan in the 14" overhead vent. The trailer's original owner told me this fan had a mind of it's own and he finally cut the wires to it as he could not figure out how to shut it off. Well I hooked up those wires as soon as I bought the trailer as I figured he must have been doing something wrong. This fan has an "auto" setting with a thermostat and a rain sensor and an infinitely variable speed control. None of these features work right. The fan will come on in the middle of the night, dome open or close all on its own even when the "auto mode" is switched off. I installed an additional on-off switch as I also could not figure out how to turn this thing off. The rain sensor activates even when there is not a cloud in the sky. The latest issue is the speed control. It will rev up to max speed and then slow and stop and then restart. I have now disabled all of the other features as I really have no need for them but the speed control would be nice. It has a sliding switch to control speed but it is faulty.
Anybody out there have one of these models? In my last trailer I installed a fantastic vent fan and it was trouble free.
Comments anyone?