Are my A/C's working correctly?

[rickydennis01]

I have a 2018 Fleetwood Pace Arrow 38N with 2 13,500 BTU A/C's. The RV is a little over 39 ft. I am new to RV'ing and don't really know what to expect concerning the cooling capacity of these units. I have heard they should be able to keep the coach 20 degrees cooler than the outside temperature. Back in July, we were at the Outer Banks and it was hot. The outside temperature was 91 degrees. The inside temperature according to the display reading was Zone 1 95 degrees and Zone 2 88 degrees. I know that these readings were incorrect and that the interior of the coach though uncomfortable was not that hot, but I did not have separate thermometers to verify the actual coach temperature.
A few weeks later during a service call, I had the dealer check the A/C units and they said they were working fine.
I was not convinced, so this past week I decided to run a test. I had the thermostat set at 75 degrees for both Zone 1 and Zone 2. Over the last few days, I have registered the following results with the RV closed (entered only to check temp) and all shades pulled. I was using separate thermometers for each zone as I know for sure I can't trust the temp reading on the display panel.
1) Outside temp 84; Zone 1 77; Zone 2 75
2) Outside temp 88; Zone 1 77; Zone 2 75
3) Outside temp 83; Zone 1 75; Zone 2 75
4) Outside temp 87; Zone 1 80; Zone 2 79
5) Outside temp 85; Zone 1 76; Zone 2 76
6) Outside temp 90; Zone 1 82; Zone 2 80
7) Outside temp 89; Zone 1 79; Zone 2 78
😎 Outside temp 90; Zone 1 81; Zone 2 75
I am concerned that there were several instances where the A/C's were not able to maintain the 75 degree setting even with the RV completely closed up and no one going in and out the door. I have, again had the dealer check the A/C's and am being told that they are functioning correctly. I contacted Fleetwood with questions about the cooling capacity and they were absolutely no help.
My question,am I expecting too much from these A/C's and is this pretty typical or do I have an A/C issue that is going to make camping unpleasant when the weather turns hot again?
Thank you all in advance for any comments you may have.

[Big_Katuna]

My 15k and 13.5K units keep my 38 Fleetwood mid 70s in 100 degree temp.

Yes, the window shades are down and I use a sunscreen on the font with curtains pulled. Filters and evap coils clean. Thermostat set on 71.

The 20 degree is a differential. 90 in 70 out but as the room starts to cool from the 70 air, the room temp drops. Now it’s 85 in 65 out. Now it’s 80 in 60 out.
Ad infintum until the compressor starts cycling. In 100 degree weather that’s around sundown.

[wa8yxm]

I have heard they should be able to keep the coach 20 degrees cooler than the outside temperature.

Close but I can understand the confusion

The outlet temp should be about 20 degrees cooler than the inlet as measured at the evap.. But keeping the RV cooler. in full sun. that's a whole nutter kettle of fish.

30,000 BTU's is simple not enough (two 15000 btu roof top units.. If you stick a thermometer in the cold air outlet and measure it should be about 20 degrees colder than the hot air intake on the A/C. Alas 30,000 BTUs of A/C can't keep up with 50,000 BTUs of SUN.

[dougrainer]

lenr wrote:
OP needs to find an RV AC specialist, which is generally not an RV dealer.

Where would an RV AC specialist work if not at an RV Dealer or RV service Center???????????? Doug

[justALnow]

If you don't have slide toppers . . . get them.

[lenr]

OP needs to find an RV AC specialist, which is generally not an RV dealer.

[doxiemom11]

We spend a summer in N Mex sitting in the sun at about 5,000 elevation. Usual daytime temp was 95 - 108. The windshield is the biggest culprit for letting heat into the rv, even with curtains drawn. Get the reflectix for the windshield. It is sold in large rolls especially for motorhomes. That will make about a 10 degree difference. Keep shades drawn, have a fan moving the air around and you will be cooler. We also have insulation pillows in our vents to keep the heat of the sun from coming thru them. Skylight doesn't seem to be a problem with it's two layers. We are 36' with 2 13,500 btu and only ran the 2nd A/C late afternoon when the sun was shining on 1 side of the motorhome and onto the windshield. We were comfortable.

[rk911]

the only way you're going to be comfortable in 100-deg temps is to...

- use one of two types of windshield sun screen...externally mounted permitting you to see thru the windshield or internally mounted creating perpetual night inside. either will reduce interior heat well. we've had both and prefer the externally mounted types.

- use a couple of small fans to circulate the cold air. cold air sinks. you'll be more comfortable by moving the air around.

- when possible park facing east or north. that will reduce direct sunlight on the windshield which acts like a radiator.

- on *especially* hot days bring in the slides. that will reduce the sq. feet that need to be cooled. the same applies to *especially* cold days or nights when heating the coach.

[wildtoad]

As others stated, outside temp is irrelevant. After making sure that the coils are clean, filters are clean, check the temp of the air going into the AC at the return against the air coming out of the AC at the nearest point. And yes depending on your setup, make sure that there is proper separation between output versus return. Many times the install was shoddy and cool air goes back up the return.

[DownTheAvenue]

dougrainer wrote:

3. Since you have ducted ceiling units a common failure by the maker is to NOT install the hot intake and cold exhaust separator in the roof mount plenum. This allows cold air to be drawn and lost back into the intake and will drastically lower cooling capacity. Doug

Definitely check this. The A/C's may very well be working correctly, but if not installed correctly, they will suffer in their ability to cool the RV.

[Big_Katuna]

Did either you or the dealer check/clean the evaporator coils?

Made a big difference on mine.

And once again Doug is spot on. My acs are set on 71-72.

[dougrainer]

The first thing you have a problem with is your reliance on the SET Temp of each AC. Setting a RV tstat at 75 in hot possibly humid weather and expecting the unit to get to 75 degrees is not feasible. There is a big difference between an RV and a HOME in insulation factors. What you should do is simple. Set BOTH Zones at 65 degrees and do your test again. You also need to start the test at night to allow the RV to get to temp without the trying to overcome the daylight sun and heat. Starting out at a good cool 65 to 70, then see how it keeps up. There a 2 tests for correct AC operation on a RV
1. NOT completely accurate but close is a 17 to 22 temp difference between the intake filter and the nearest Cold air exhaust to the AC unit
2. A Compressor amp draw test corrected for outside ambient. This is how a qualified RV Tech should do it.
3. Since you have ducted ceiling units a common failure by the maker is to NOT install the hot intake and cold exhaust separator in the roof mount plenum. This allows cold air to be drawn and lost back into the intake and will drastically lower cooling capacity. Doug

[zigzagrv]

I think two 13.5k BTU a/C's SHOULD be fine. My 33' has a single 13.5k a/c and it has always kept us comfortable in 90+ degree temps. Spent two months a few years ago, July and August, in Branson with daily temps in the upper 90's to 100+ degrees and it kept us comfortable. Granted, we were in the shade about 70% of the day.

Recently returned from a trip to Mo, Tx, Al, and N.C. and it was hot and humid, but my single 13.5k unit kept us comfortable even in full sun much of the time. I don't have double pane glass or extra insulation....just a plain mid-level coach.

[lenr]

Aggree with Old-B on the temperature difference range. However, my experience is that the difference between intake and out blow will drop toward 15 degree as the outside temperature approches 90 degrees or as the AC unit ages. I use my wife's internal meat thermometer to measure the temperature up in a duct.

[rickydennis01]

Thanks for the response. As soon as this hurricane goes by and I can get the RV opened up again, I'll check and see what that temperature reading is.