Our main a/c isn't cooling our 38RD enough

[Randalf]

The main a/c on our 2016 38RD simply isn't getting the job done. Our 5er is parked beside our house in Central Texas while we get ready for our first major road trip with it. The daily temps are in the low 90s, but the living room a/c only brings down the living room temp 14-15 degrees. Yesterday it was 92 outside, and 78 inside.

The bedroom a/c works as expected. If the thermostat says 74, that's what the room temp is. The living room thermostat usually reads higher than what the actual temp is, and turning it down to 68 still only gets it into the upper 70s. The trailer does sit broadside to the evening sun, but solar screens and blinds are kept down, and the a/c is kept on all day to get a head start on the evening sun. I also have two vents from the the bedroom and bathroom turned into the hallway to help out in the living area. No cooking is being done to raise the temps.

I've heard that typical fifth wheels can only be kept about 20 degrees below ambient, and I found that to be true with our previous 5er. When we parked our Chaparral 36 on an asphalt lot in Las Vegas, with the sun beating down from dawn til dusk, it would stay 80 when it was 101 outside.

So why isn't my higher-end "Residential Vehicle" doing much better than an entry level "Recreational Vehicle"?

[RCAircraft]

Originally Posted by Randalf

The main a/c on our 2016 38RD simply isn't getting the job done. Our 5er is parked beside our house in Central Texas while we get ready for our first major road trip with it. The daily temps are in the low 90s, but the living room a/c only brings down the living room temp 14-15 degrees. Yesterday it was 92 outside, and 78 inside.

The bedroom a/c works as expected. If the thermostat says 74, that's what the room temp is. The living room thermostat usually reads higher than what the actual temp is, and turning it down to 68 still only gets it into the upper 70s. The trailer does sit broadside to the evening sun, but solar screens and blinds are kept down, and the a/c is kept on all day to get a head start on the evening sun. I also have two vents from the the bedroom and bathroom turned into the hallway to help out in the living area. No cooking is being done to raise the temps.

I've heard that typical fifth wheels can only be kept about 20 degrees below ambient, and I found that to be true with our previous 5er. When we parked our Chaparral 36 on an asphalt lot in Las Vegas, with the sun beating down from dawn til dusk, it would stay 80 when it was 101 outside.

So why isn't my higher-end "Residential Vehicle" doing much better than an entry level "Recreational Vehicle"?

Check the discharge temperature at one of the A/C outlets. Should be about 55 F. If close then check for any blockage in the duct work beginning at the A/C unit. Many have reported finding blockage at the A/C unit.

[ted 95]

How many ACs do you have 2 or 3?? you don't say. We have a 2015 38GK and we can bring the temp down to 65 when it is 95+ outside. We usually keep it at 70 to 72.
Are your fans on high on each thermostat?? If they are not on high they can freeze up.
Are all the returns open??
Is the air really flowing??
The return filters are they clean?? the black foam things can get really dusty.
The temp should be about 20deg+ difference from the room temp coming out of the round vents.
Is the front closet closed. cause the heat loves the front cap.
From there you can go on the roof and remove the cover. maybe you got leaves or something on the fins and it is not cooling properly

[johnboytoo]

I found on our 13 38gk that turning vents from the rear air actually hurt the cooling up front because the placement of the front thermostat made it 'fool' the thermostat into thinking it was cooler than it was...

Without a generator to pre-cool the rvm what we found was no matter what we did, it would take 4 to 6 hours to cool down the 5'er initially, but after that it could keep up !
we tried leaving slides in, covering windows, fans, leaving residential freezer open nothing seemed to help, so we would plug in, turn ac's on full blast and leave until the sun went down that first night.

[Randalf]

Our unit is a 2016 model (but built 10/7/2015), and has two roof units. They are both Coleman Mach a/c's and are apparently both 15k heat pumps. I say this because they appear identical, and the manufacturer's equipment list says it has "30,000 BTU a/c".

Ted 95, the filters are clean, and air is blowing from every vent. The fan is on low in the bedroom because that unit doesn't have any trouble keeping the front of the trailer cool. The closet door is open (because I'm lazy) but it has it's own a/c vent in it, so it stays plenty cool in the cap area. Right now it is 90 in the shade outside. The bedroom thermostat is set at 74, it says it's 74, and that is what my handheld thermometer says is the actual temperature in the bedroom/bathroom/closet area.

Ahh, but the kitchen/living area! As I said, it's 90 degrees ambient outside, and 106 when the thermometer is placed in the direct sun. The rear unit thermostat reads 83 right now, even though the a/c is set to 66. The fan is on high. My handheld thermometer says it is 79 here at my easy chair, and the a/c has been running around the clock. That's as good as it gets in the evening.

Johnboytoo, our unit is stationary and I'm staying in it full-time, so the a/c's run all day. I hate to think what it would be like to pull into Vegas in the heat of the day and have to open the slides and try to cool it down when it's 100+ outside! Here in Texas it still drops into the 60s at night, so in the morning the whole trailer is cool & comfy. It doesn't get any morning sun because of a hill, and it stays comfortable until after 2 pm when the sun passes over and hits the broadside of the trailer. Then the temps climb to uncomfortable levels, even though I've been "pre-cooling" the trailer all day.

RCAircraft, I'll have to get a tester to get accurate temps/flow rate. My "open palm test" indicates pretty uniform flow, but I doubt it's blowin' at 55. More like 65, I'd guess.

[Ford truck guy]

Have you checked how far the ac collars go inside the ducting? A lot on here had to trim them back ( including me ) because they were 1" or more too long. I did that and noticed a big difference. My unit is black, and i am able to keep it in the low 70's on a hot summer day with no shade in Florida..

[Randalf]

Ford truck guy, I haven't tried any troubleshooting yet, I'm still trying to figure out where to start looking. We bought the trailer four months ago, so I'm still getting to know it.
I don't want to do anything to violate the factory warranty, but I also don't want to have to make an appointment at the dealership, then haul it 45 miles and leave it while they spend days working on it. I like to do my own repairs when possible, so I appreciate all the info you guys are giving me.

[johnboytoo]

As a temporary measure,
get you some reflectix here or here, cut it to size and push it into the window openings to line the windows on the sunny side,
stuff some up into the vent when they re not in use,
cover the shower skylight on the outside to keep the sun from beating down on it...

I know, I know, but to keep cool, I sure would !

put your awning out and tie it down - do anything to keep sun off...

[travelin' texans]

As Joe (Ford truck guy) said, remove all your outlets & check the height of the collar & depth of the duct, if I were to guess you'll find a 1 1/2" collar in a 2" duct so essentially they block the duct , several have trimmed them down to let air flow by. I would also turn both units to high fan & add a couple small fans to move the air around.
Also the gasket between the return air plenum & the output in the unit on the roof has probably slipped out mixing outside warm air with the cool. You'll have to remove the a.c. cover & several screws on the metal cover to inspect that gap, I along with others put the foam gasket back & covered the gap with a.c. duct foil tape.
Last fall when we arrived in Arizona early afternoon it was 114 outside & 94 inside once setup & it took about 1 1/2 hours to get to the 74 I had set the thermostat at.

[johnboytoo]

one other thing - do you have halogen or led light bulbs ?

AMAZING the amount of heat those little halogens produce !

The Best RV Accessories For Cooling Off In The Summer

[Randalf]

All right, guys, I'm ready to do battle! I'm back from town and I'm armed with an infrared thermometer gun and a bunch of beer. I reckon I'll have a beer and install the batteries in the gun, then have a beer and read the instructions on how to use the gun. Then I think I'll have a beer and.... take a nap. THEN I'll get up and start taking temps, and remove the vents from the ceiling to see what lies beneath. Do those round rotating vents just snap on?

I have noticed a disparity in the temp that the hall thermostat reads. It usually reads substantially higher than actual indoor temps, so at first I assumed it was showing the outdoors temp. This morning I set the thermostat at 74, and it now reads 75. But my handheld thermometer says it's actually 69 in the hallway where the thermostat is, and 71 on the couch at the back of the trailer.

[Ford truck guy]

Originally Posted by Randalf

All right, guys, I'm ready to do battle! I'm back from town and I'm armed with an infrared thermometer gun and a bunch of beer. I reckon I'll have a beer and install the batteries in the gun, then have a beer and read the instructions on how to use the gun. Then I think I'll have a beer and.... take a nap. THEN I'll get up and start taking temps, and remove the vents from the ceiling to see what lies beneath. Do those round rotating vents just snap on?

I have noticed a disparity in the temp that the hall thermostat reads. It usually reads substantially higher than actual indoor temps, so at first I assumed it was showing the outdoors temp. This morning I set the thermostat at 74, and it now reads 75. But my handheld thermometer says it's actually 69 in the hallway where the thermostat is, and 71 on the couch at the back of the trailer.

Those rings SNAP off, with the gentle help of a butter knife..
That will expose 3 small screws that hold the fixture in... Remove those screws and you will be able to PULL the fixture out of the ceiling.
measure the thickness of the ceiling, then measure the ring.. You will probably see that the ring needs to be trimmed by an inch or so for better flow..

Once done that, ( and the 6 pack) . Its time to climb to the roof and call us back ! The AC foam divider is next !

[travelin' texans]

You should save the roof job for tomorrow BEFORE the cold ones, if your like me you don't bounce well.

[Randalf]

I don't know if I've discovered anything meaningful yet, but I'm having a lot of fun with my new thermometer gun (it has a laser beam on it!). And also with my Guinness Irish Wheat beer & Shiner Golden Ale.

So, after my nap, I decided to check the depth of the vent rings first. I started by pulling a bedroom vent off, since I could reach it without a ladder and easily figure out what you guys are telling me to look for. That duct is only 1 1/2" deep, and the ring is 1 1/2" tall. However, there is an inch of space between the ceiling and the duct, so the ring only protruded about a 1/2 to 3/8th's into the duct, leaving about an inch of unobstructed duct. The circular cuts through the ceiling and the bottom of the duct are very tight, and it was hard to reinsert the collar through the openings, so I'm not losing any air there.

Once I understood what I was looking for, I checked the other five vents in the bedroom/bath via flashlight and by sticking my finger in through the louvers. They were all installed in the same way, with the same inch of clearance in the duct. When I used my super-cool thermo-gun (with laser!), each vent read 47 degrees from a distance of 18".

In the living room I got readings of 52 from the kitchen vents (closest to the a/c unit), and 58 at the rear vents. I haven't pulled any of the vents off, but I can see via flashlight that they all have the same 1 1/2" rings, BUT none of the rings are properly inserted through the holes in the bottom of the air duct. They all appear to have simply been pushed up against the bottom of the duct, and I can see that there are small gaps around the rings and the bottom of the duct. But none of them are protruding into the duct & blocking air flow.

Now here's a quick caveat: it was cloudy today, so there was no direct sun on the trailer when I was taking my readings. It only got up to 88 outside, so the trailer stayed plenty cool inside. It's 5 pm here now, the clouds are gone, and the evening sun is starting to shine on the side of the trailer. I'm going to let it heat that wall up for a bit, and then grab a Guinness and my thermo-gun (with laser!) and get some outside & inside temps on the wall. Stay tuned.

[Randalf]

Travelin' Texan, the highest I'm going to climb tonight is up the three steps into the bedroom. My wife is in Colorado with my daughter and grandkids, so if I fell off the roof I'd have to lie there for weeks waiting for someone to fetch me another beer.

[travelin' texans]

Originally Posted by Randalf

Travelin' Texan, the highest I'm going to climb tonight is up the three steps into the bedroom. My wife is in Colorado with my daughter and grandkids, so if I fell off the roof I'd have to lie there for weeks waiting for someone to fetch me another beer.

That's a good plan, you could die the thirst before she got back.

[johnboytoo]

Yes, stack your empties up next to the 5'er to keep the sun off it !!!
It STUNNED me the heat difference between the different colors on ours...
I know black absorbs heat, but my goodness !!!!

Why I suggested getting the sun off at any cost...
do you have awning covers ?
How about window awnings ?
on our new MH, those windows awnings are worth their weight in GOLD in two ways...
Keeps the sun off the windows on the passenger side AND keep the hot air to a minimum when the wife says I can't see outside with the shades drawn

[Randalf]

You are so right about the colors, johnboytoo! When I went out at 6:30 it was partly cloudy, so the sun wasn't even close to doing it's worst. I still got a temp reading of 110 from the cream colored paint, and 124 from the maroon paint. The windows were reading 111 on the outside, 101 on the inside, and 90 through the blinds & solar screens.

I'm ready to check out that foam gasket on the roof tomorrow. I also have vent covers to install over the kitchen & bath vent fans, so I'm hoping it's cloudy again tomorrow morning.

By the way, I do have all LED lighting in the trailer, no halogen anywhere.

[homeguy]

The only thing I see that I would look into is Sam Adams Summer Ale and Shiner Bock. Not familiar with the Golden Ale but I'm willing to try new things. Our thermostat for the living room reads high also, very common for these things as I am on my 3rd thermostat.

[Foxfire]

Originally Posted by johnboytoo

As a temporary measure,
get you some reflectix here or here, cut it to size and push it into the window openings to line the windows on the sunny side,
stuff some up into the vent when they re not in use,
cover the shower skylight on the outside to keep the sun from beating down on it...

I know, I know, but to keep cool, I sure would !

put your awning out and tie it down - do anything to keep sun off...

A word of caution. JMHO Putting this stuff behind the windows could cause a problem. It could cause the windows to break due to thermal shock. No where in the product literature does it say anything about using it by the windows. Putting it behind the windows would cause the glass to hold more heat than they are intended to. The insulated glass could fail and the monolithic glass could break. I don't think its a good idea. I would try other things first.