After several years and keeping my AC vents closed on the AC units, I am not sure this is best way to cool. This forces all the air into the little round vents scattered along the interior roof. Today it was 101 here in Texas so we are loading to escape the heat. (Better late than never). Going to the 6 state FMCA Rally in Sedalia, Mo. I opened the vents under the unit and a lot of cold air came thru and still had lots of volume at the little round vents. Which is better??? Closed or open under the ac unit ??? I am thinking a little open and this pushes more air out. Can you give me your experience and what is correct?? DAN
We tried air conditioning with the vents under the fans open. We didn't like the additional noise. I couldn't tell a significant difference in overall effectiveness. It did seem to be more effective at cooling the area immediately under the A/C unit. That can be important when lights, hot water, and hair dryer heat up the bathroom area.
By opening the vent on the A/C unit you get an air dump. No restrictions and more volume, it just is not dispersed unless you have the smaller vents opened.
Under extreme conditions (outside temp>100) we sometimes open the louvers on the face of the AC unit and let the cooled air flow direction into the coach. But we also use a couple of floor fans to mix the air in the coach when the roof vents are not used. I have no data to say which is better, but it is my impression that opening the louvers is more effective (with fans) under extreme conditions.
Under these conditions we also use fans on the refrigerator condenser. I have posted on this in the past... the fans are mounted near the roof. Again, not good data to show this is worthwhile, but I think it has helped.
Tks for the input. I too have small fans I scatter around the inside on hotter days. They really help with the cooling. I think I may leave a small opening in the face of the AC and see how that works. Tks DAN
I've been messing with the vents trying different combinations for the past couple of weeks and I finally feel like I have things somewhat figured out. I actually close all the ceiling vents except for the two in the bedroom and the one at the fridge. This forces most of the cold air either into the bedroom (which I like cold) and toward the front of the coach. I found that any other way it would be freezing cold in the kitchen/dining area and still warm enough up front that the A/C would keep coming on.
I leave mine closed and just use the little vents. When it is super hot out I will try to chill the motorhome down at night. Set the ac at 67 and let it run. The morning temps will be 67 and then I can raise it a bit and the ACs will cycle till the hottest part of the day. Awnings and MCDs help a lot. Oh and I have two small fans to keep air moving and a front windshield sun screen but that area is still a heat sink.
Good info as I have the same coach
Bob