The tap tapping during the night, though can be the outer door, on ours its the inner flap, thats part of the vent housing, that is the source of noise. Even outer door latched it sometimes flaps.
wnjj s mod is very clever but it wont work (as easily) on all vents. I was going to copy but the opening and duct on our vent housing considerably smaller than outside vent. So the latches would need to be really long.
The sheathed cable also works.
Mine has gone thru a few different motors, Muffin fans work great, however the one I originally picked up, on high, was only 80cfm. While Margaret could snooze while I made coffee-the camper filled with steam. I never revisited but a higher cfm muffin/cpu fan still be nice also because of low power use.
I subsequently put in a salvaged can motor from a printer. Direct fit, quite, but again just didn't move enough air. Currently Im running the stock motor but added a resister and double throw switch to make it 2 speed similar to factory 2 speed. Sound not bad on low but on high, to actually vent, its the same old too loud motor.
We also use the fantastic to vent,that works really well but on cold mornings also takes all the heat.
IF I ever get a wild hair it would be to gut the vent housing and get rid of the horizontal fan- reduct so it draws horizontally heat/air thats being captured by hood instead of same level as bottom of hood. Thats why it needs such high CFM, just to overcome poor design of the box. But I'm really surprised someone doesn't make a retrofit kit using pancake or muffin fan.
