Our 32B does the same thing the rear bunk room would get HOT! I just closed off 3/4 of the vent. another one of the vents is partially in the bathroom. I made a diverter out of some thin gauge aluminum to put most of it into the living area. our front bedroom always got warm so I left that vent alone and the one in the main living area never did put out much heat, niether did the one in the bathroom before I did my mods. I now have balanced heat in the trailer.
It`s like blowing through a straw, cut a hole in the middle of the straw and blow through it, you will likely not feel any air coming out of the hole. now block some of the airflow coming out of the end of the straw, you should now feel the air flowing out of the hole. a staright run heat duct works the same way. take a couple of phone books and block some vents you should feel the air coming out of the other registers.
02 Ford Excursion V-10 4.30 gears 5 Star Tuner Y-pipe mod Hellwig sway bar Rear Airbags
Prodigy and Dual Cam
07 Cherokee 32B
Better to have a bad day of camping than a good day at work!