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Old 05-29-2013, 12:02 PM   #1
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Question How cold should A/C output be?

It has gotten real warm (ie hot) here in North Florida and it seems like my A/C can't keep up. I checked it with a instant read thermometer the other day and the output was 52 degrees. It seems to me the it should be blowing colder than that. I have 2006 Rockwood 8280SS not sure what A/C is in it I do know it is a 13.5K just now which brand model as it is at a campground nearby that we go to when we can sneak away. Is it possible to recharge the coolant in the A/C or is it a sealed system?
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Old 05-29-2013, 12:08 PM   #2
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Heard that anywhere between 15-20 degree cooler than incoming air is about normal, anymore than that is a plus.
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Old 05-29-2013, 12:10 PM   #3
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52 degrees ? WOW thats awsome !
shade plays a big part on keeping your rv cool.
I would say your camper will mostly hoover around 10 degrees below outside ambiant temp while maintaining low levels of humidity.
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Old 05-29-2013, 12:23 PM   #4
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Originally Posted by f1100turbo View Post
52 degrees ? WOW thats awsome !
shade plays a big part on keeping your rv cool.
I would say your camper will mostly hoover around 10 degrees below outside ambiant temp while maintaining low levels of humidity.
Campground where it is sitting does not have any shade. The only reason I am asking is our friends that we camp with have a new Keystone Sprinter and their A/C doesn't run nearly as long between cycles as ours. Are the newer A/Cs more efficient and move more air?
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Old 05-29-2013, 12:28 PM   #5
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they may have a ducted a/c unit wear as you may not ?
they may have a 15k whereas you may have a 13.5 k ?
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Old 05-29-2013, 12:33 PM   #6
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I agree 20 or so degrees cooler than intake air is standard. So, if your camper is 72 inside you are right on target, if it is 82 you are beating the odds.

It has been my experience that no two of them function the same. Plus, your friend may have 15,000 and you have 13,500... in the same conditions theirs would be doing better.

Another point to consider their units may have a different level of insulation in the ceiling, that would make the greatest difference.
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Old 05-29-2013, 12:33 PM   #7
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they may have a ducted a/c unit wear as you may not ?
they may have a 15k whereas you may have a 13.5 k ?
Mine is ducted into the kitchen, LR and bedroom they may have a 15K though. Would it cool more efficiently if I closed the main duct on the unit and allowed it to just run through the other ducts?
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Old 05-29-2013, 12:48 PM   #8
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Mine is ducted into the kitchen, LR and bedroom they may have a 15K though. Would it cool more efficiently if I closed the main duct on the unit and allowed it to just run through the other ducts?
It most likely will cool better by using the ducted portion.

The main duct is considered a "quick" cool method.
Allowing cold air dumped into main room right after starting unit.

I'd try to let it flow through your ducted system to other rooms.

Also keep all your shades pulled during daylight hours as that also helps a bunch.

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Old 05-29-2013, 01:11 PM   #9
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I keep my shades closed but even then the heat gets through. I think it is the number of windows. I have the Super Slide with 5 windows and you can feel the heat radiating around the metal frames. We have the camper paid up at this spot until June 16, I don't think we will go back to this particular CG until it cools off. I just like the fact that it is fairly close and I don't have to mess with setting it up every weekend.
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Old 05-29-2013, 01:57 PM   #10
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Get some of this stuff and cover your roof vents inside as well as your large windows when you are out. It will cut the heat tremendously in the unit.

Reflectix 25-ft x 48-in Radiant Barrier - Lowe's Canada
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Old 05-29-2013, 02:09 PM   #11
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Op- from what I've seen-
The usuall rule on ac output is 50-55 is optimal for vehicles and I would venture that most others as well. The best I have ever attained was 42 on a real humid day and less than a dozen under 50 in my 12 years doing it, most seem to be 52-54.

That is just my experiance- mainly on vehicles, about 3-5 of them a week . Of couse ducting and distance will play a factor.

I'm sure other ac guys will chime in here in a bit.
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Old 05-29-2013, 02:10 PM   #12
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Quote:
Originally Posted by RickV View Post
It has gotten real warm (ie hot) here in North Florida and it seems like my A/C can't keep up. I checked it with a instant read thermometer the other day and the output was 52 degrees. It seems to me the it should be blowing colder than that. I have 2006 Rockwood 8280SS not sure what A/C is in it I do know it is a 13.5K just now which brand model as it is at a campground nearby that we go to when we can sneak away. Is it possible to recharge the coolant in the A/C or is it a sealed system?
AC experts say if an ac unit keeps the interior 20 cooler than the outside ambient temp. that's all you can ask. Anything more is a bonus.
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Old 05-29-2013, 02:45 PM   #13
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Get some of this stuff and cover your roof vents inside as well as your large windows when you are out. It will cut the heat tremendously in the unit.

Reflectix 25-ft x 48-in Radiant Barrier - Lowe's Canada
I already have the roof vents done with these Amazon.com: Camco 45192 Sunshield RV Vent Insulator: Automotive but I like the the Reflectix idea for the windows. I assume you use velcro to attach them to the windows. After you cut them to size how did you finish the edges of the Reflectix?
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Old 05-29-2013, 03:14 PM   #14
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Do you have a slide cover over the Supper slide? It sounds like you have a (Atrium slide),if so they are a Heat Producer. Youroo!!
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Old 06-14-2013, 02:58 PM   #15
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We've never had any problems with our AC not keeping up. When it was topping out at 105 last year it worked hard but kept it at or below 80 inside without a problem but as a rule I always look for simple ways to improve things. We keep our blinds drawn and I plan to put reflectex in the bathroom skylight and vent, and the skylight in our slideout just to go easier on the AC.

As for how cold my air gets it was 92 outside the other day with 75% humidity and full sun. We stayed at 74 in the trailer with the AC only kicking on high twice and our indoor humidity stayed below 37%. Out of curiosity I checked the air coming out of the vents with an instant read meat thermometer and it said 38 degrees. I didn't believe that at first so I got a different thermometer and sure enough, 38-40 degree range whenever the AC is on. This is a Dometic 13.5btu roof mount unit by the way.

My AC mods from last summer:
I made sure all duct work was sealed good by using the wife's small cosmetic mirror to have a look. Everything there was fine so I wasn't leaking air at the ends of the ductwork and cooling the whole roof. Next I noticed the vents weren't sealed and cold air was escaping into the interior of the roof. I sealed around the vent insert and the ductwork with aluminum tape and solved that problem.

Next was the unit itself. I took the plastic cover off and made sure there was no way air could get between the return and duct sides then made sure to tape and seal all joints with more aluminum tape between the roof and ductwork. There was A LOT of room for improvement here as far as sealing air leaks goes.

To improve noise I covered my dump vent with more tape. I never use this vent and the fins were causing a lot of wind noise. With the tape over the dump vent on the inside it cut down on noise by over 40% I would say.
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Old 06-15-2013, 10:18 AM   #16
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52 is good!

Most people are under the impression that a unit that comes on and quickly cools the space to your thermostat's setpoint is doing a good job. The reality is that that unit is probably oversized for the application. In Florida we have to deal with high humidities. Short runtimes do not allow the coil to stay sufficiently cold (55 degrees) to dehumidify the supply air. A unit is better sized if it has longer runtimes to cool to setpoint and will therefore do a good job at keeping the humidity down. The bottom line is that you want your AC to have a supply air temperature of about 55 degrees, run long enough to dehumidify the space and be able to get down to a reasonable cooling setpoint of about 74-76 degrees. It shouldn't cycle more than about 6 times an hour. If your supply air isn't coming out at around 55 degrees you may have a mechanical issue that needs attention. It may simply need a charge of freon to get it back down to temperature but it should be done by a qualified tech. If the charge was low to begin with, why? It may have a leak and adding freon will do nothing but help empty your pocket. Shading and insulation are also very important. As a matter of fact, I am looking for some shade cloth myself. I am fortunate to be parked under a nice live oak but need to cut the direct sunlight on my west side windows in the late afternoon. Next project!

Hope that was helpful.
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Old 06-15-2013, 11:39 AM   #17
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Your A/C temp output is determined by your intake or the temp in the unit. In the industry it is called a delta T . You should get between 15 to most 20 degree drop from the return air temp. That is to say if your unit inside is 80 degrees the best you can expect to come out is 60 degree air. As your temp drops inside, your output will will also drop. The more humid it is outside will also count against you. Think of the a/c as a big dehumidifier. That is why a unit will work better in Calif. then Florida. You could be getting less cooling in only 2 ways. being under charged or over charged which is the worst.
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Old 06-18-2013, 04:00 PM   #18
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Florida in June will be an issue for any RV that is 30 or more feet with a 13,500 btu AC. I live in SE Texas which has summer weather like Florida, if not worst and my 32 foot V-Cross 275 fiver has 50 amp and two ACs, 15,000 in living area and 13,500 in bedroom. In the heat of the day anywere around here in late spring, summer and fall both ACs run most of the day to do the job. Under normal conditions you can only expect a 21 degree drop from outside temp. Good Luck
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Old 06-19-2013, 08:00 AM   #19
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Florida in June will be an issue for any RV that is 30 or more feet with a 13,500 btu AC. I live in SE Texas which has summer weather like Florida, if not worst and my 32 foot V-Cross 275 fiver has 50 amp and two ACs, 15,000 in living area and 13,500 in bedroom. In the heat of the day anywere around here in late spring, summer and fall both ACs run most of the day to do the job. Under normal conditions you can only expect a 21 degree drop from outside temp. Good Luck
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