furnace duct work, only coming out of 1 vent strong

Probably crushed tubes. on my trailer I had a similar issue, but my duct work is built into the floor. the bunkroom you could almost roast a turkey and the kitchen duct had next to nothing coming out of it. I closed off the bunkroom vent by 70% which forced the heat out the other vents. it takes a bit of work but now the entire trailer is comfortable.