we have a 378 and I found that air would come through the dash vents if the ac/heater switch was in an on position. Turned it off and no problems. We have been out all winter and have not had a cold up front situation. The fireplace keeps the whole coach warm down to about 40 degrees, then i turn on the rear furnace. The only time the front furnace has been on is to check to see if it works.
defending FR I must say that the coach is well designed and really quite maintenance free. We are in the middle of a 5000 mile trip.
JimF, CWO, US Army Ret, 100% DAV
2011 Georgetown 378TS
2008 Dodge Caliber Toad