MORE info needed. 1997 Monaco should have had a Norcold 1200 as OEM. So, if you have a residential, that means someone in the past 26 years modified the cabinet. The original refer, you should have a outside access door AND a Roof vent above the Cabinet. This means if the previous owners modified the cabinet they must have blocked off this source of fresh air ventilation. Leaving the original outside door and roof top vent alone would provide more than enough fresh air for any residential installation. Let us know what has happened to the original access vents. Doug