I have a 1999 Winnebago Adventurer 34V diesel pusher. I have only a small port just forward of the air filter intake and aft of the sewer connection door. This is the heater port that says HOT. I do not have a hatch or removable door on the outside like on other models. Does any one know how to gain access to the heater for inspection? Any one know of any handy youtube videos that reference this? Thank you.