How long should it take the A/C to get cold inside in hot temps?

[trekhard]

So I've done research and know that the A/C CAN only get down about 20 degrees from outside temp.  Questions:  how long should this take???

At pickup last year, we were really late getting out of orientation, overheating, and newbies.   it took us a longtime to set up camp, in and out of the camper door. Not only as newbies, but Oliver hadn't yet set up the cushions (anti-humidity batting was still in bags) and we had a lot to do....  We never cooled off.  It was sooooooo hot and we didn't get good sleep.  Hit the road, next night next to a brewery where we couldn't plug in.  The battery seemed to drop off very fast and we only ran the A/C one hour before turning it off so we had some power.  NO sleep, terribly hot and sweaty.  It took another day on the road before the solar charged up the battery, and then we were home.  Since then, all of our camping has been plugged in, but we didn't need the A/C.   I am quite worried since we have our dog with us and will be boondocking.  Does our A/C work?  I don't know.  It felt cold coming out but just didn't cool off the camper.   How long should it take to cool off in hot temps?  Does it really work?   I went in an expensive camper with a mini-split and it was cold and quiet.   

[SeaDawg]

I'm not the best person to respond,  as we rarely use ac, but, I'd definitely test it out, take notes, and open a service ticket while you are still under warranty, just in case.

 

 

[Mike and Carol]

Have you plugged in at home and tried it out?  You’ve got the thermostat set right?  I’ve never run the AC on batteries, but on shore power it gets cool in 10 or 15 minutes.  On our way back from the rally we had a couple of hot stops in Texas and the AC cooled us down pretty quickly.  Mike

[trekhard]

17 minutes ago, Mike and Carol said:

Have you plugged in at home and tried it out?  You’ve got the thermostat set right?  I’ve never run the AC on batteries, but on shore power it gets cool in 10 or 15 minutes.  On our way back from the rally we had a couple of hot stops in Texas and the AC cooled us down pretty quickly.  Mike

We will have to do this.  After an hour was still hot in the trailer, yet cold air was coming out of it so we thought it was working, but we just don’t have the trailer experience to know…It was cold under the AC but not too cold.  And once it was turned off was hot again.  

[Landrover]

When I have someone who’s interested in seeing  my  Oliver, I will turn  the Ac on about 45 mins before showing.  I open all the cabinets to let the Ac circulate throughout the entire hull.  The temp will be at 74dgs the automatic fan goes to low. It is quite cool and the noise level is minimal.  This is in Florida temps in the 90s. In short 45mins🥶

[Mike and Carol]

Have you tried adjusting the vents?  Open the ones on the sides and back if they aren’t already.  What temperature do you have the thermostat set at?After an hour it should be plenty cool inside the trailer.

[Trainman]

9 hours ago, Mike and Carol said:

Have you tried adjusting the vents?  Open the ones on the sides and back if they aren’t already.  What temperature do you have the thermostat set at?After an hour it should be plenty cool inside the trailer.

I agree, vents and thermostat setting are critical for setting the temputures to your liking. The thermostat is a little harder to figure out at first and paying attention to the symbols does take a little to get the hang of it. I think it cools ok, but the noise of the unit is my biggest gripe.

trainman  

[topgun2]

Yep - after and hour I'm cold unless I forgot to close a window, the MaxAir and/or the bath fan.🤪

Since you are in the West I assume that you have not noticed a reduction in humidity levels or noticed a drip from the little hose on the exterior rear street side of the Ollie?

Bill

 

[Scott and Frieda]

On a related note, I'm curious what to expect with humidity levels? I'm not seeing a difference between outside and inside humidity levels. Shouldn't the AC reduce humidity in addition to temperature? I'm using a MarCELL to measure inside temp and humidity so I assume it's accurate. What have others experienced in regards to expected humidity reduction?

[topgun2]

37 minutes ago, Gooey said:

Shouldn't the AC reduce humidity in addition to temperature?

Yes - assuming that you have the "standard" air conditioner, the condensate will flow from the overhead a/c unit down a tube that is located between the shells and exits at the bottom of the Oliver via a short tube at the rear street side.  While operating in humid conditions you should see water dripping from this tube.

While at the recent Owner's Rally I observed this very thing happening on my Elite II.

Bill

[Chukarhunter]

Your question sounds straightforward but the answer is complicated and multi-dimensional.  Cooling a hot trailer to the preferred set temperature is a function of the capacity of the AC expressed as the hourly maximum Btu's of heat that the AC can extract from the inside of the trailer versus the heat gain into the trailer from the outside.  My AC is rated at a maximum of about 13,500 Btu/hour so I will use that as an example.  If the trailer is absorbing heat from the outside (heat gain)  at a rate greater than 13,500 Btu/hour, than the air conditioner will not be able to cool the inside of the trailer at all.  It will be doing well just to keep the inside from heating to  warmer than the outside.  If the outside temperature is 95 degrees and the heat gain is 7,000 Btu/hour, then 7,000 Btu/hour of AC cooling capacity will offset the heat gain and the remaining 6,500 Btu of cooling capacity is available to actually cool down the inside to the preferred temperature setting.  If the outside temperature is 105 degrees and the heat gain is now increased to 10,000 Btu/hour, then there is only 3,500 Btu/hour of cooling available to actually lower the inside temperature and it will take longer to cool the inside.  As the inside temperature falls relative to the outside temperature,  heat gain will continue to increase. 

Heat gain is a function of the several factors, the most important being the difference between the outside temperature and the inside temperature.  The good news is that compared to most trailers, the heat gain in the Oliver is on the low side if the user cooperates.  This lower heat gain is a function of many design attributes including the insulation between the hulls, the white outside color, the tinted windows and the "tightness" (very few penetrations of the hull) that minimizes the number of outside air exchanges per hour.  To get the most out of your air conditioner, you must park your trailer in the shade, make sure all windows and vents are closed tightly, and don't open the door unnecessarily.  If shade is not possible, extending the outside awning can help reduce heat gain in the trailer somewhat as can closing window shades.

The speed with which one can actually cool down a hot trailer is a function of how warm the inside is to start with (stored heat in the thermal mass of the trailer itself) and the excess cooling capacity of the AC remaining after offsetting the ongoing heat gain from the outside.  There are things you can do to achieve the best performance upon arrival on a hot afternoon.  After minimizing heat gain to the extent possible by parking in the shade, etc. , make sure that the trailer is closed up as tight as possible by closing all windows, hatches, doors and vents to the outside.  Then turn on the AC and set the thermostat down as low as it goes, and open all the inside vents on the AC itself to maximize airflow through the heat exchanger.  You will want to turn the thermostat down way low because you want the compressor in the AC to run continuously until the trailer cools to the desired temperature after which you can reset the thermostat higher to hold the desired temperature.  I have concluded the Dometic thermostat in my Oliver does not work very well.  It will cycle the compressor off and on unnecessarily, even when the inside of the trailer is still well above the set temp.  By setting the set temperature down to say 60 degrees initially, the hope is that the compressor will run continuously until the trailer is cooled .  Any cycling will greatly increase the time it takes to cool the trailer.

While the trailer is cooling down , stay outside if possible and try not to open the trailer door unnecessarily until it has cooled down inside.  A human body adds several 100 Btu's an hour and two persons inside can easily add 500 Btu's an hour to the cooling load.  Opening the door several times can do the same.  Once the trailer has cooled inside to your desired set temperature or below, you can move inside, raise the thermostat setting to your preferred set temperature and the AC  should cycle normally to maintain the inside temp you want.

[Scott and Frieda]

Thanks for the detailed reply, @Chukarhunter. Very helpful!

[trekhard]

Thanks everybody.  I didn't see replies so just now looking back at my post.  I think what happened is that we were loading the trailer while trying to cool it and that just didn't allow for cooling at all.   When the door stays closed, we finally had cooling!!!

[trekhard]

ps- I'm not sure how to reply to just one person.... or how to select a quote directly.  

 

Thanks Chukarhunter.  I think the door was the reason we couldn't get cool!!  

[jd1923]

On 8/13/2024 at 12:30 PM, trekhard said:

ps- I'm not sure how to reply to just one person.... or how to select a quote directly.

You can click the word quote, hit the + sign to the left of the word for a multi-quote. You can highlight a portion of a post and click "Quote Selection.

Or just type the ampersand character and start typing the forum member's name like I'm doing here with your name: @trekhard

You should get two notifications from my message, one for quoting you and another for the mention using your forum name (alias).

[Jason Foster]

I have the Truma, and it takes about 25 minutes to get to comfortable levels at 98-degree exterior temps in the sun.

[srthomsen]

We were in Floresville, Texas last summer at a BMX event and the daytime temps (real temps. not "feels like" temps!) while there did not drop below 109 degrees during the day. 

We have a small 2023 Elite with the Truma Aventa A/C system and after arrival that first afternoon it cooled the trailer down in about 25 minutes to a nice comfortable 79 degrees. 

During the following three days the interior temp never rose to above 80 degrees.  It worked flawlessly.