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Old 06-16-2021, 08:34 PM   #1
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Basement A/C Performance

We are in Sedona, Arizona and day temps are 110 degrees while night temps are 100 degrees. The basement AC in my rig con’t seem to drop the inside temperature any lower than 95 degrees. It’s generating good flow from all vents and the air seems cold. Should it cool better than that?
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Old 06-16-2021, 10:00 PM   #2
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The actual cooling differential depends entirely upon the insulation values for the MH, if the main duct-work behind the rear cap is fully sealed, if the evaporation coil is clean and clear for proper air flow and heat transfer and if all the windows are covered with insulating material.

You should be seeing a Delta of approx. 20įF between chilled air exiting the vents and return air at the filter.
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Old 06-16-2021, 10:57 PM   #3
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see the above reply. but there are some things you can do to help out your AC.

- if you're in a motorhome and you have the option park facing either north or east. that will reduce the amount of sunlight that hits the windshield. the windshield acts as a radiator causing enormous amounts of heat to enter the coach.

- the best way to reduce the radiated heat from the windshield is to use an exterior mounted windishield sunscreen. we use a Magneshade but there are numerous manufacturers. the sunscreen won't eliminate all heat but they do a very good job. interior sunscreens are very inefficient at keeping heat out. the idea is to prevent the windshield from heating up.

- cold air drops to the floor so use a couple of floor fans to move that cold air around.

- on really hot days (or cold days) we close the bedroom slide and maybe even one of the front slides to reduce the amount of sq. feet that needs to be cooled (or heated).
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Old 06-17-2021, 07:46 AM   #4
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Shade ... man-made or otherwise is a critical factor. In those temps I always try to park with the rear to the afternoon sun and use awnings as much as possible... minimal side exposure to the sun.
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Old 06-17-2021, 08:07 AM   #5
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It's cooling the coach 15 degrees in that heat - it's doing pretty good! As said above, use a windshield screen (on the outside is best), keep shades down, put awnings out, and of possible run water over roof to act as a 'swamp cooler'.
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Old 06-17-2021, 10:21 AM   #6
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Thanks for your suggestions. We are fortunate to have gotten a site with the windshield facing north and trees on both sides. Window and patio awnings are deployed. Night shades are down. We purchased a roll of that silver insulation stuff from Home Depot and today I will be cutting a piece to fit the windshield. Temps are expected to reach 114 today so we will see how it does today.
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Old 06-17-2021, 12:45 PM   #7
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I would also recommend running the A/C all night with t-stat set to 60 deg.

We were on our way back to So Cal from Minn and stopped in Las Vegas for 5 days in August. It was worse than I expected with no shade and high temps around 115-118 deg and lows in mid 90's.

With the A/C running all night, the inside temp by 6 am would get down to about 60-62 deg and we were wearing light coats to keep comfortable. Then inside temp would slowly creep up, 70 by 9 am, 80 by 11 am, 90 by 1 pm and peak at around 94. We could tolerate the 80's inside, but 90+ we would leave for shopping, movie theater, or casinos. Our last night the rv park lost power around midnight and our choice was run the genny or leave. We did both, ran the genny and left at 4 am to cross the desert and get to SoCal at 9 am.

The Winnie coaches that are painted black (or dark colors) up on the roof radius and front/rear caps, with black aluminum window frames .... that's where a huge amount of heat is transferred inside. My 1999 Winnie was all white from compartment doors up, and we did just fine with 24k btu basement A/C and 115 deg for a week. This coach is 6 ft longer with larger slideouts and will do ok up to 105 deg along with all the insulating measures folks use.

Summers in Arizona is ok if you can get above 6000 ft elevation. Sedona at 4200 ft isn't going to be very comfortable during a heat wave. I see the ave Sedona temp should be around 82, that would be great!
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Old 06-17-2021, 01:42 PM   #8
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Your basement AC has two compressors. When you turn on the AC, quickly go outside and listen to the basement unit. First compressor goes on immediately and second compressor goes on after about 15 seconds (providing your thermostat is set about 3 or more degrees lower than ambient temp).

If you don't hear the 2nd compressor kick in, you won't get the full cooling performance of the AC.

I had that situation and it was caused by my power management system malfunctioning and shutting down my 2nd compressor thinking it was preventing the breaker from tripping.
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Old 06-18-2021, 07:22 AM   #9
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Yesterday, when we returned to our campsites after a day of sightseeing, the outside temp was 108. We were pleasantly surprised to find our rigs inside temp was 88. Thatís 6 degrees better than the previous day and with only 5% humidity itís a comfortable temperature. It seems the shade and windshield insulation has helped.
Jerry & Susie
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Old 06-22-2021, 04:27 PM   #10
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I put foil sunshades in all windows. At 110 degrees, the ac will run non stop and not keep up. These units are not that well insulated not sealed.
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Old 06-22-2021, 09:51 PM   #11
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Yes indeed the front windshield is like a big magnifying glass so covering that from the outside is critical in high temperature as is having outside covers on the roof vents with insulating pillows on the inside. The tendency for coaches to be painted darker colors though will cripple your AC as will cooking meals that tale a long time or require boiling water along with long steamy showers. Long sessions with a hair dryer too will raise the temperatures in your coach as will running Plasma TV (really any TV), using computing devices that tend to run hot and high power sound systems.

Regular cleaning of both the evaporator and condenser coils along with changing the air filter are also key points to remember with the relatively small air filter potentially requiring attention every week or two especially when its mounted in a location noted for accumulating dust like on the floor under a bed.

Since I live in the Deep South and do much of my camping here dark colored coaches were automatically passed by and not even a consideration. Don't buy one if your planning on camping in extremely hot locations is the best advice I can give you.
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Old 06-23-2021, 06:48 PM   #12
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We live in the Fresno area of Central California, last week we expected 106 to 110 degree temps, we only have swamp cooler on the house no ac. So what I did was went out to the RV and started the generator, it was 99 inside, with in 2 hrs it was 80 degrees. The dog, new kitten and I were very comfortable until late evening when we could come back into the house. The basement air on our rv has always worked well and quieter then the overhead units in other rv's. I would have the unit checked.
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