‘21 Cougar 368mbi ducted AC issue

[Colbat3]

New member here. I have a 2021 Cougar 368mbi with 2 AC units. The main cabin AC (Coleman Mach 15) is ducted only, the dump vents are disabled. I live in coastal South Carolina and this setup does not cool the main cabin. The bedroom gets really cold. With both ACs running in 95 deg heat, the main cabin was 85 and the bedroom was 72.

Is there a way to rectify the problem without replacing the main AC unit?

[jsb5717]

The bedroom AC should also be ducted. if you close the dump vent it should move a lot more air through the ducts. That’s how ours is set up and it works quite well when both AC’s are working through the ducts.

[chuckster57]

Welcome to the forum

Dump vents disabled?

Does your AC have the returns on the edges?

[jsb5717]

By the way…welcome aboard! You’re at the right place. It does sound like you have the “Whisper Quiet” AC in the living area. No dump vent, just return vents off to the side. That’s what we’ve got. My earlier advice should help keep the whole coach cooler. Our bedroom gets cooler faster and warmer faster…that’s just how it is.

[Colbat3]

Ahh. So if I turn on both units and close the dump vents in the bedroom it will send more air through the ducts and therefore cool the whole RV. I’ll give it a try this weekend! Thanks!

[chuckster57]

You should take off the vents and make sure the ducts are sealed to the ceiling, and look at the end vents, often times the duct goes all the way to the end, wasting cool air. Seal the ends just beyond the last vent for even more cold air flow.

[sourdough]

IIRC on the 368MBI there have been complaints of the mid room only having one vent. The layout of that trailer and the way they vented it can pose some cooling problems IMO. Closing the dump feature is for sure what you need to do to get things going for the entire RV. I would also suggest replacing the vent covers with some that you can close along with placing a fan in the bedroom facing the living area to push that cooler air toward the living area. I replaced 4 of my vent covers with some that I can close. I had 4 vents in the bedroom wasting air IMO and shut off 2. I also shut off the one to the bathroom as leaving the door open between the living area and bedroom with a fan keeps it OK for as long as we stay in there.

[Colbat3]

That makes sense. Definitely had problems cooling the mid room and I was surprised that you couldn’t close the duct vents. I actually used a blower on our last trip to move air from the bedroom to the main cabin. Worked pretty good. Getting me vents that close..

[Ground Whip]

Cobalt, I have the same model 5th wheel only a '22. I've been in the 90+ degree weather for several weeks on the Texas coast. At night, I keep the main unit at 71 and bedroom unit 70 both on auto fan and they cool as advertised. In the morning, the main goes to 75 degrees with with the fan on auto. The bedroom to 73 with the fan on high for the day. The main will rise to 77 at most mid-afternoon and the bedroom stays at 73. When I set them both to 75 on auto, the main area would go to 82-85 midafternoon and the bedroom would go to 70. Because of the venting being connected, keeping the bedroom blowing moves the cool air back. I checked all the vents and did not have leaking like some have suggested. Hope this helps!