AC Losing Battle

[Wellplayedsir]

Hi I have a 2021 RL 3781 and they AC can't seem to keep up, in the morning after running all night it is at 75 deg. But as the day warms up they inside temp keeps rising even with both units on high by mid afternoon it is 90 deg with an outside temp of 100 deg. {Florida} We close the shades and have they awnings out to help shade a little we even put a reflective white coating on the roof to no avail. they air feels cool comming from the duct so I am stumped why there is only 10 deg diff from inside temp to outside temp.

[Vaughlw]

Are both AC units running?

[Wellplayedsir]

Yes like I said both units running on high.

[rohrmann]

If you are in a high humidity area, it will be harder to maintain a comfortable temperature in your rig. The A/C is having to not only cool but is also having to remove a lot of moisture.

[Daryles]

Check your air returns for gaps. Our Rear one had a gap big enough for two fingers to fit through into the attic. The front one had a 3 finger gap. Close the gap with metal foil tape. Trim back any obstruction in the plastic return.

[Wellplayedsir]

Originally Posted by rohrmann

If you are in a high humidity area, it will be harder to maintain a comfortable temperature in your rig. The A/C is having to not only cool but is also having to remove a lot of moisture.

I just find 10 deg difference is unacceptable, it is hot and humid in other parts of the country am I they only one that has this problem. What is they average between inside and out temps.

[Wellplayedsir]

Originally Posted by Daryles

Check your air returns for gaps. Our Rear one had a gap big enough for two fingers to fit through into the attic. The front one had a 3 finger gap. Close the gap with metal foil tape. Trim back any obstruction in the plastic return.

I will check that out thanks.

[Foldbak]

Exactly what Daryles said. It sounds like you're losing air flow. The newer systems are much better then the older and yours is a 2021. What AC units do you have? Coleman? Go on YouTube. You'll find so much information there!

[Wellplayedsir]

Originally Posted by Foldbak

Exactly what Daryles said. It sounds like you're losing air flow. The newer systems are much better then the older and yours is a 2021. What AC units do you have? Coleman? Go on YouTube. You'll find so much information there!

Will do thanks.

[Vaughlw]

The back ac on our 2021 the compressor would not come on. Fans ran fine but no cooling. That's why I asked if we know for sure both ac units are operating correctly. Air will still come out of all of the vents in the coach even if only 1 is running. it will still be a struggle to keep it cool during 100 degree days unless you add the third ac unit. Good luck,

[rames14]

You have an issue, whether it is ductwork or compressor not coming on as mentioned. Running one AC at a time, check the air temp coming out using a thermometer (they make them just for that purpose or use optical pyrometer). If you have the same temp (probably about 20 degrees below ambient), then check ductwork for flow. If one of the AC’s is not putting out cold air, then it’s time to check that AC.

[team bradfield]

Florida in the summer is always a tough job for the AC's

[phillyg]

We're in SWFL and we usually see at least a 20+ degree difference continually using both ACs, morning and night. I have to think your ducting may be compromised and/or the vents need trimming. It might be a good idea to run a camera through the ducting looking for blockages or gaps where air could be escaping to the attic. You might also want an HVAC tech measure the AC performance, too.

[skippydoo]

We have 2019 HC, 331RL new.

. Came with Domenic AC
2x 15K ac's
1 is a quick dump in the bedroom

Live in the Carolinas and travel only into hot and humid weather.

We manage to lower our rig's temp to around 63-64', in Fla during the summer months when temps top 95plus. I am not joking. We are freezing.

But, at first this was not the case. ..after watching many youtube videos, husband spent hours with his hand's and arm's inside vents, taping, pushing and pulling out junk that builders forgot. He also made cones that are secure to 2 vents near door, to force air flow DOWN verses OVER the ceiling.


When you have your air on, you should feel it. You should not have to search around, stand at a different place, trying to feel a trickle of air---somewhere, maybe coming out.
I honestly don't know what we are going to do when we trade. We sat in a new rig abt 1 month ago---hooked UP and AC on at dealer. We asked the sale's guy, where is the air flow?
His response was, oh here (hand at vent) you can feel it a little it takes time. As he was moving around trying to feel it himself.

We need a manufacture who is based in the south. None of this new junk would be installed to appease the complainers who live UP north and don't like the air sound.

Please keep us updated. You are not the first with this problem. So sorry.

[skippydoo]

Originally Posted by Wellplayedsir

I just find 10 deg difference is unacceptable, it is hot and humid in other parts of the country am I they only one that has this problem. What is they average between inside and out temps.

YOU are correct that is NOT NOT NOT acceptable.
Plus, you are not the only one who has gone through this.

[Wellplayedsir]

I am having some techs come over to take a look next weekand and will follow up.

I use to wonder why anyone would need three AC on there RV, now I know.

[DavidG425]

www.shaderv.com

Keeps the sun from heating up the roof, which in turn keeps the ducts from heating up.

In SoCA, it could be 110 outside, but a reasonable 76 inside.

[bcrvman]

Originally Posted by Wellplayedsir

Hi I have a 2021 RL 3781 and they AC can't seem to keep up, in the morning after running all night it is at 75 deg. But as the day warms up they inside temp keeps rising even with both units on high by mid afternoon it is 90 deg with an outside temp of 100 deg. {Florida} We close the shades and have they awnings out to help shade a little we even put a reflective white coating on the roof to no avail. they air feels cool comming from the duct so I am stumped why there is only 10 deg diff from inside temp to outside temp.

Block the furnace cold air return.

[VagabondLove]

This really helped for me….

https://www.montanaowners.com/forums...ad.php?t=83870

[pitman44]

First, as someone mentioned measure the supply air and the return air temperature. There should be about a 20F difference. If there isn't a difference at all the compressor is not making cold.

Next, pull the grill off the bottom of the AC. The supply is on one side of the unit and the return on the other. They are most often separated by a piece of insulation put in by the RV factory. The static pressure difference between the supply and return air is HUGE. It's very easy for supply air to short circuit to the return side and that will kill the effectiveness of the AC. In fact there's a company that makes a custom fit foam block that eliminates that problem. Google "RV Air Flow". It should come right up.

In any case, make sure there is a very good seal between the supply and return. Also check the foil tape between the box and the ducts. Make sure they're sealed well and not blocking air flow. And make sure the box is sealed so air can't blow into your attic.

Then I would pop off a couple of the supply grilles. There's a tube that sticks up into the duct. In our Montana HV, they were sticking up too far into the duct. IMO sticking up into the duct at all is too far, but ours were 3/4" or so up into it. I took them all down, cut the excess off, put them back in and resealed them to the duct.

Finally I cut every other fin out of the grilles. All of these changes made a HIGE difference in how well our AC cooled our rig. I hope these help you.