The first time my wife turned on the exhaust fan on the microwave because she was cooking something on the stove (This was in January and too cold to cook outside). I told her I would go make sure the air was coming out of the vent. That was when I discovered it had tabs and I am 6'1 and I just barely have enough height to push the tabs up (standing on the tips of my toes) to open the vent. I always shut the vent cover as part of my packing up the RV from the campsite because I don't want any bugs or dirt getting inside.
2013 Columbus 295RL
2006 F350 6.0L Crew Cab LB SRW