New tenants who so far had to have an emergency locksmith out the night they moved in because the lock (only 3yrs old) jammed. Now reckon they replaced the charcoal filter on the exhaust fan over the stove and it is blowing air out rather than sucking it in and want a serviceman out there. Anyone have any clues whether they could have altered something to do that, or do recirculating fans suck in clean air through the charcoal filter and then blow it out?