Journey with Confidence RV GPS App RV Trip Planner RV LIFE Campground Reviews RV Maintenance Take a Speed Test Free 7 Day Trial ×
RV Trip Planning Discussions

Go Back   iRV2 Forums > MOTORHOME FORUMS > Class A Motorhome Discussions
Click Here to Login
Join iRV2 Today

Mission Statement: Supporting thoughtful exchange of knowledge, values and experience among RV enthusiasts.
  This discussion is proudly sponsored by:
Please support our sponsors and let them know you heard about their products on iRV2
Thread Tools Search this Thread Display Modes
Old 08-07-2022, 08:52 AM   #1
Junior Member
Join Date: Sep 2017
Location: Toronto, Ont.
Posts: 2
Question Air Conditioning question for everyone

Hello RV world ... fairly-newbies here.

We are having weather this summer in Toronto that is really warm. Consistently over 40 degrees with the humidity (which is lots) factored in. Early mornings it is still about 22, with high humidity. During the day we are both away for work.

Our question is about leaving the A/C on during the day when we're away. Is it more efficient to just leave it on, set to perhaps 23, and let it cycle on and off throughout the day, or turn the whole thing off whilst we're away, and let the coach get mighty warm, and turn on the A/C when we return at the end of the work day?

We're interested in two major aspects ... energy use (we want to be kind to the planet), and actual cooling efficiency (we want to be kind to us).

2007 Itasca Horizon 40 coach with a Coleman Mach basement A/C that works very well. No issues.

What is everyone's advice? We want to hear all sorts of suggestions, thoughts, opinions, experiences.

Martin12345 is offline   Reply With Quote
Join the #1 RV Forum Today - It's Totally Free! RV Community - Are you about to start a new improvement on your RV or need some help with some maintenance? Do you need advice on what products to buy? Or maybe you can give others some advice? No matter where you fit in you'll find that iRV2 is a great community to join. Best of all it's totally FREE!

You are currently viewing our boards as a guest so you have limited access to our community. Please take the time to register and you will gain a lot of great new features including; the ability to participate in discussions, network with other RV owners, see fewer ads, upload photographs, create an RV blog, send private messages and so much, much more!

Old 08-07-2022, 09:02 AM   #2
Senior Member
Join Date: Jul 2014
Posts: 31,230
With the AC is cycling thru the day keeping the RV cool, it's also keeping the humidity down.

Switching it on after it bakes in the heat is going to make it run full time for many uncomfortable hours cooling down the hot RV. Not to mention the humidity it needs to remove.

I leave mine set at 78F while not in use.
twinboat is online now   Reply With Quote
Old 08-07-2022, 09:05 AM   #3
Senior Member
Join Date: Aug 2019
Location: Eastern outskirts of Dallas, TX
Posts: 2,168
Several problems with MoHo’s and RV’s to contend with -

The exposed surface to volume ratio is horrible. Exposed surface allows for more thermal infiltration.
Not only is the thermal infiltration bad, but so is the infiltration of moisture or humidity.
It takes ~1000 times more energy to condense 1# of water than it takes to cool 1# of air 1 degree F (not C). A pound of air takes up about the same volume as a residential refrigerator here in the US (don’t know about our Canuck friends to the north) - 14.7 cu. ft.. And - you have to condense water if your going to air condition air. Even in the “dry” desert.

A long route to take to answer your question. In the end, it would roll the stat back to 80 - 85 (F, not C ��) and live with it. You’ll keep the moisture saturation of the permeable things in the coach at bay during the day so as to shorten the amount of time it takes to cool the coach on your arrival.
91 Ultrastar Champion02 Georgie Boy Landau 8.1l Workhorse
03 Jeep Wrangler TJ 2018 Jeep Wrangler JK toad
MrMark52 is offline   Reply With Quote
Old 08-07-2022, 09:51 AM   #4
Senior Member
DRM901's Avatar
Tiffin Owners Club
Texas Boomers Club
Join Date: Feb 2018
Location: North Texas
Posts: 1,289
We turn it up several degrees (3 C) warmer when we aren't there. Not so much that it takes hours to get down to the temp you want when you are there. However, if we are staying at a campground where the hydro is free, we do cheat and probably only put it up a degree or so.

You do want it to run regularly to keep the moisture down. Or run a dehumidifier if really humid.
2014 Tiffin Allegro Bus 37AP
DRM901 is offline   Reply With Quote
Old 08-07-2022, 09:53 AM   #5
Senior Member
96 Wideglide's Avatar
Holiday Rambler Owners Club
Join Date: Aug 2010
Posts: 9,027
I would raise the temp a couple of deg while away, but, you don't want your rig to heat up. Once that floor / furniture/ counters get hot, it takes a lot of AC to cool them back down.
Ben & Sharon
2008 43' Holiday Rambler Scepter PDQ
96 Wideglide is online now   Reply With Quote
Old 08-07-2022, 12:45 PM   #6
Senior Member
Ray,IN's Avatar
Join Date: Aug 2001
Location: North America somewhere
Posts: 26,769
Originally Posted by twinboat View Post
With the AC is cycling thru the day keeping the RV cool, it's also keeping the humidity down.

Switching it on after it bakes in the heat is going to make it run full time for many uncomfortable hours cooling down the hot RV. Not to mention the humidity it needs to remove.

I leave mine set at 78F while not in use.
Me too!

Without air conditioning/dehumidifier running, all the stuffed furniture, carpet, clothing and mattress is absorbing humidity which must be removed in order to cool the air properly to a comfortable level.

Example; many years ago my dad insisted on installing an air conditioner with 2X the required capacity. The end result was cool, very moist air that was uncomfortable for occupants of the house.
2000 Winnebago Ultimate Freedom USQ40JD, ISC 8.3 Cummins 350, Spartan MM Chassis. USA IN 1SG 11B5MX,Infantry retired;Good Sam Life member,FMCA." My fellow Americans, ask not what your country can do for you, ask what you can do for your country. John F. Kennedy
Ray,IN is offline   Reply With Quote
Old 08-07-2022, 01:10 PM   #7
Join Date: Jul 2021
Posts: 34
I believe, if you are worried about resources, RV's are not the way to go.

fredbon is online now   Reply With Quote
Old 08-07-2022, 02:29 PM   #8
Moderator Emeritus
Gary RVRoamer's Avatar

Join Date: Jan 2000
Location: Silver Springs, FL. USA
Posts: 25,322
I'd set it to about 27C while away for the day, but I'm a Florida boy and don't think that is even hot. Are you going to be distressed when you get home and have to wait on hour to bring it down to whatever you like? Is that 22C or 23c? Maybe even 24C?

I'm confident you would not tolerate it if you left the a/c off all day, especially if the coach is in a sunny spot. Temps inside would climb to 32C or more.
Gary Brinck
Former owner of 2004 American Tradition and several other RVs
Home is West Palm Beach, FL
Gary RVRoamer is offline   Reply With Quote
Old 08-07-2022, 02:57 PM   #9
Senior Member
Join Date: Mar 2019
Posts: 896
Install a WiFi enabled thermostat. Raise it when you leave a few degrees. Lower it via WiFi an hour before you get back.

Or, if your schedule is pretty steady, get a thermostat with built scheduling and use that.

As others have said, you are not just cooling the air, you are cooling all of the thermal mass of the RV.
bentjm is offline   Reply With Quote
Old 08-07-2022, 09:45 PM   #10
Senior Member
Join Date: Jan 2009
Posts: 4,088
I'd definitely let the a/c run during the day. But as others have suggested, raise the stat setting a bit. Myself, 28C (about 82F) would do fine.

I run that setting in both the house and the motorhome down here in humid southeast Texas when I know we're going to be gone for the day. Humidity stays manageable and it doesn't take long to cool things down once the thermostat is set back down.
03 Itasca Sunova, Workhorse P32 with the 8.1 and 4L85-E
Mudfrog is offline   Reply With Quote
Old 08-07-2022, 10:18 PM   #11
Senior Member
wog099's Avatar

Tiffin Owners Club
Join Date: Dec 2018
Location: Nacogdoches, TX
Posts: 767
I always leave the air conditioner on when gone for the day. Just adjust it up a few degrees and it's fairly comfortable when I return and easy to cool down a few degrees if needed when I return.
Would never consider leaving it off when it's hot.
Wade & Debby Griffin
2018 Tiffin Allegro Open Road 32SA, Ford F53 24K Chassis
2012 Jeep Liberty
wog099 is offline   Reply With Quote
Old 08-08-2022, 09:42 AM   #12
Moderator Emeritus
TXiceman's Avatar

Ford Super Duty Owner
Join Date: Aug 2000
Location: Full Time, TX Home Base
Posts: 22,098
Blog Entries: 21
If you raise the temperature too much, the A/C will have a long way to pull the space back down when you return. In addition to the air, it has to cool all of the walls, cabinets and furniture.
Amateur Radio Operator (KE5DFR)|Full-Time! - 2012 6.7L Ford Crew Cab Dually -2013 HitchHiker Champagne 38RLRSB - Travel with one Standard Schnauzer and one small Timneh African Gray Parrot, retired mechanical engineer
TXiceman is online now   Reply With Quote
Old 08-08-2022, 06:55 PM   #13
Senior Member
Skip426's Avatar

Join Date: Apr 2011
Location: Powell River, B.C.
Posts: 27,564
When you arrive home at 40c ,ambient temperature, even 30 inside the coach will feel good.
At 22 c after a half hour inside the shock of going outside to do anything will hit you like a bag of bricks .
Set for 28/30 when you leave for the day , gradually reducing temperature towards bedtime, after you arrive home.
When still living at home , the house had central A/C , mom had temperature set at 72f;21c, I’d go home for lunch ; outside temperature 105+; after 45 minutes in the house,going back to work outside was torture, and I was only 19. I had to stop going home for lunch just sat in the shade with my sandwich.
99DSDP 3884, Freightliner, XC, CAT 3126B, 300 HP /ALLISON 3060
2000 Caravan toad, Remco & Blue Ox.
Skip426 is offline   Reply With Quote
Old 08-08-2022, 08:41 PM   #14
Senior Member
Join Date: Apr 2018
Posts: 2,224
If I'm out working in the heat I can't cool down internally if the temps are over 72. I think our metabolism up here in the north functions very differently than when living down south. I do kick the temps to 78 if I'm gone all day. The ACs run pretty hard all evening when I return.
shootist is offline   Reply With Quote

air, air conditioning

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Similar Threads
Thread Thread Starter Forum Replies Last Post
Dash Air Conditioning: Cabin Air Filter? RTegarini Workhorse and Chevrolet Chassis Motorhome Forum 3 06-24-2018 07:42 PM
Chassis Air Conditioning Question Volunteer Fleetwood Owner's Forum 8 09-09-2010 03:05 PM
Dash Air Conditioning putting out hot air Keith727 Newmar Owner's Forum 19 08-19-2009 08:44 PM
Another GNR Question - Air Conditioning??? sightseer 30B Winnebago International Travelers Club (WIT) 6 01-29-2008 05:31 PM
loss of air conditioning and fresh air through vents cwg Newmar Owner's Forum 2 03-31-2007 06:45 PM

» Featured Campgrounds

Reviews provided by

All times are GMT -6. The time now is 08:03 PM.

Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2022, vBulletin Solutions, Inc.