I have read a number of discussions on this and apparently the MaxxAir Fans were not designed with a broad enough range of acceptable voltage. I have read of quite a few failures of MaxxAir Fans on discussion forums, and on one someone even quoted the MaxxAir specs which had a max voltage of less than 14 volts. Why this would designed that way is beyond me. I think that may be a non issue with newer manufacture models.
One thread did discuss a voltage regulator to install in the supply power to the fan.
Something similar to this was installed behind the trim or elsewhere in the fan circuit to stabilize the voltage.
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