This is a common question by from owners of newer rigs. Here is one of many discussions which describes the problem and solution (Hint: fan on Auto)
http://www.montanaowners.com/forums/...ad.php?t=63365
You really should have posted this questions as a new topic. This questions gets lost in a multi-page unrelated topic and will be difficult for others with the issue to find it. Plus use the "Search" tool in the upper right corner of the page. Most Montana problems have been asked and answered already.
As for Art-n-Marge, technology has passed you by. Your 10 year old rig has a completely different thermostat and technology.