Can't keep bedroom cool.

[shortedout96]

I have a new 2016 Sprinter 293FWBHS... I have tanker it out for the second time this weekend. I am having issues keeping it cool for some reason. The rear bunk house and living room get cold but the upper bedroom doesn't. I bought vent that I could shut air off to bunk house and living room thinking it would ouch more air up front but that doesn't seem to be working. Also for some reason the front bedroom only has one vent. My old camper was a 98 Holiday Rambler 5th wheel and I had no issues cooling it and pretty sure it only had a 13.5 a/c unit versus this one having a 15k unit. The other camper had more windows for the heat to get in and cold air to ex ape so doesn't make sense why I can't keep this camper cool with on a/c unit. Any suggestions or has anyone had this issues with a newer sprinter 5th wheel.

Thank You
Adam


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[therink]

The first thing I would do is buy a roll of foil tape, remove all ceiling vent covers, examine to make sure the ceiling openings are well sealed so that cold air isn't flowing into the ceiling cavity. It is common for the factory to do a sloppy job foil taping these areas.
Next, remove the inside AC unit cover. Examine the plenum area and ceiling duct openings (there will be two openings/ fore and aft). Make sure all foil tape is neat and there are no obstructions to hinder air flow into the ceiling ducts. There is a vertical divider between the return and supply sides of the plenum. Make sure there are no air leaks between the two sides. Retape as needed.
The next thing I did was place cardboard (neatly held in place with foil tape) into the ceiling ducts just past the front and rear most vent openings. I noticed that the ceiling ducts continued on past the two end ceiling vents to a dead end. By closing off these areas, there was a noticeable increase in air flow out the end vents.
In my unit there is also a ceiling vent in the upper bathroom (just aft of the front bedroom). I removed the vent cover in the bathroom and covered 50 percent of the opening with black duct tape. This helped increase flow to the front bedroom and still allows enough flow to keep bathroom cool.
Using these techniques greatly improved the air flow and efficiency of my AC.
I hope this helps you.

[ReadyToRoll]

Had the same problem with our Cougar TH. As it had air in the garage, blocked the opening and also restricted the bath vent about 3/4. Also, in the living room, had a vent blowing out only about 3' from the main ac vent. That I restricted as well and now have plenty of air and cool in the bedroom. Still cools the living room well.

[Face Down]

Heat rises, cold air sinks. Since your 5er has a sloped roof you are always going to struggle to keep the bedroom cool as it is the highest point of the unit. Your best best is going to be to add a 2nd AC unit to that area.

[instymp]

Heat rises, cold air sinks. Since your 5er has a sloped roof you are always going to struggle to keep the bedroom cool as it is the highest point of the unit. Your best best is going to be to add a 2nd AC unit to that area.

or buy a fan that blows air upstairs.

[jlarocca]

I have the opposite problem from the OP. My Montana Mountaineer 346LBQ stays plenty cool up front (we have a bedroom A/C Unit) and the living room and back bunk room are hotter than hades. The unit came with a 13.5K unit and I had them upgrade it last summer to a 15K and it is still uncomfortable in here. My whole family winds up sitting in the front bedroom. I'm down on the Gulf Coast right now and it's in the upper 80's and its miserable in here. The air flow out of the vents through out the unit seem to be pretty decent and the air coming out is plenty cold it just won't cool the unit. Doesn't even catch up at night after dark? Suggestions? I've had this thing in multiple times for this issue and to two different dealers and they say the units are working fine.

[SteveC7010]

I have the opposite problem from the OP. My Montana Mountaineer 346LBQ stays plenty cool up front (we have a bedroom A/C Unit) and the living room and back bunk room are hotter than hades. The unit came with a 13.5K unit and I had them upgrade it last summer to a 15K and it is still uncomfortable in here. My whole family winds up sitting in the front bedroom. I'm down on the Gulf Coast right now and it's in the upper 80's and its miserable in here. The air flow out of the vents through out the unit seem to be pretty decent and the air coming out is plenty cold it just won't cool the unit. Doesn't even catch up at night after dark? Suggestions? I've had this thing in multiple times for this issue and to two different dealers and they say the units are working fine.
If the rig has been in the shop several times for this problem and two different shops have assured you that the A/C is working normally, then I would start to look beyond the A/C units.

First, though, does the main unit have the capability to pull in outside air? If it does, you'll want to make sure that is closed all the way so that you are only recirculating inside air. Our cars and trucks work the same way. Hit the max button and the recirculate light comes on and the outside air intake is shut off.

Secondly, is the trailer closed up tight? If there's open windows and/or doors, you're constantly heating up that colder air. I'm not saying you are doing that, but more asking that you look at everything.

There may be a source of hot air that is overlooked. The cold air return on my furnace kind of draws on the basement of the trailer as well as the living space. In the cold weather, I make sure that is closed up so I am pushing cooler air only from the interior of the trailer back to the furnace for reheating. Same principle applies for your A/C. If there's an open path into the basement, and maybe even on to the outside, you could be pulling a lot of unwanted warm air into the right.

Put a thermometer on the output of the bedroom A/C and determine what temp it puts out. Then do the same on the main A/C. They both should put out about the same temp.

There's a vent control on the plastic face of the A/C. Slide it one way, and you get a tremendous blast of cold air out that panel. Slide it the other way and the air flow stops and more cold air is pushed to the other ceiling vents.

On the topic of the ceiling vents, we're had several folks report blocked heat ducts resulting in poor heat circulation in colder weather. I think it is worth doing your own check on that for the A/C ducting. Drop the round plastic covers off the vents and use an electrician's fish tape to make sure the ducting is clear of any obstructions.

Lastly, check the main thermostat for accuracy. You may find that it needs to be set lower than is indicated on the panel. I've got the old Duotherm slider type in my Cougar, and the temps printed next to the slider have no obvious relationship to reality. I keep reminding myself that I need to do the digital upgrade soon.

[Bob Landry]

The Rink is correct on all counts.Everything he mentioned need to be done before looking at anything else. I have no problem cooling my Outback227 with a single 15K BTU unit. Drop the return air grill and stick your hand up in the plenum chamber(carefully). If you feel ANY cold air in that cavity, break out the foil tape and get busy. That will cost you a lot of cold air and the unit to possibly short cycle.

[jlarocca]

Thanks guys, I've got to get a thermometer to check the output temperatures but will do that. Nothing is opened up but there is a heater vent that goes into the basement that I guess could be pulling air from the floor vents. I'll stop that vent up and see if that makes a difference. This is a brand new Dometic Duo Therm Brisk 2 Air RV Air Conditioner 15000 BTU that uses the R410a refrigerant and the air coming out the vents is plenty cold. There is no outside air option on it that I can find.