This comes up a lot. Several reasons why the vents may not be working as well.
Pull the terminal vents and make sure that they do not continue beyond that point. Some have taped with aluminum AC vent tape to block. A cut pool noodle has even been used. Regardless, the extra long run cuts down on efficiency and cools the ceiling or front and cools the end caps needlessly.
Make sure the vent caps are not too long. If they push up into the duct too far they will restrict flow out of the vent and flow beyond that point also.
Do a search on the forum and you'll find lots more information. Here's one link to get you started.
http://www.keystoneforums.com/forums...ad.php?t=28722
Welcome to the forum from Kansas City, MO! I hope you find your answers.
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