Hi. I will try and explain what those vents are supposed to do. This may help you with what you have now.
Those ceiling vents do not per say, direct the cold air. They are made to balance the AC air flow/volume in the camper. Screwing them in, CW, closes them to help choke the volume of air at that location. By choking off one area it forces more air to the other vents that are in line with it.
There are normally 2 main ducts up above the ceiling. One heads to the front and one to the back of the camper. Then in line in one of those ducts are several of those adjustable volume vents. Each main duct only has a certain volume of air leaving the main AC unit
If you have the vents closest to the AC unit wide open, then most of the cooling will be in that area and not much farther away. Again those vents balance the volume that the AC unit produces. If you put larger new vents in place of them, all the cold air will come out close to the ac unit. If that is what you are after, then they can help.
If you want to balance the amount of air to be even across the camper, start with them all only about 1/4” to 3/8” open and then let the camper cool down and the AC shut off. Then feel how even it is from one end to the other. Tweak the colder spots closed a little and open the warm ones a little. You only have so much volume to spilt up amongst the vents in the one duct.
In our bedroom, we do not want a large blast of cold air during the middle of the night, so that one vent is closed more then others.
Hope this helps.
Current Sunlines: 2004 T310SR, 2004 T1950, 2004 T2475, 2007 T2499, 2004 T317SR
Prior Sunlines: 2004 T2499 - Fern Blue
2005 Ford F350 Lariat, 6.8L V10 W/ 4.10 rear axle, CC, Short Bed, SRW. Reese HP trunnion bar hitch W/ HP DC
Google Custom Search For Sunline Owners Club