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how to work rv thermostat

How RV Heating and Cooling Really Work

Using the climate control in an RV is simple, but there are a few things that make it different than using a home system.

Understanding when to run the propane furnace vs. the heat pump, how to most efficiently run both A/C units and locating the remote temperature sensors will make the RV life a little more comfortable.

In our first year of RV travel we must have blown through hundreds of dollars worth of propane because we didn’t understand how the heating systems worked.  On the flip side during summer trips we ran the A/C almost non-stop because we couldn’t get the RV to cool down and stay cool.  Now we’re on our third class A RV and we like to think we’ve got it down fairly well, so I’m sharing a few of the tips and tricks we’ve learned over the years about Heating and Cooling an RV.

Our Excursion is equipped with two 13,500 btu low-profile Air Conditioning Units; the bedroom A/C has a built in heat pump and living room A/C does not.  We also have two propane Furnaces for heating the RV; the furnace in the bedroom is 25,000 btu and the furnace in the living area is 20,000 btu.  All of this is controlled with the industry standard digital RV Comfort thermostat controller (at least for most class A RVs).  When I asked why we only have one A/C with a heat pump I was told the A/C units without the heat pump are a lot less expensive.  So there ya go!

Thermostats and Temperature Sensors

rv temperature sensor

As with most newer RV’s the thermostat is pre-set for our specific RV climate controls.  “Zone 1” controls the living area and “Zone 2” controls the bedroom (some RV’s have 2 separate thermostats entirely).  Our RV has two remote temperature sensors (it’s that little black plastic circle with a horizontal line through it on the wall) which is totally different than a home system where the temperature sensor is built directly into the thermostat.  The first remote sensor is located just behind the driver’s seat attached to the sidewall of a cabinet and the second is located in the bedroom near the foot of our bed.  Knowing where these little thermostats are located is important for conserving propane in the winter and electricity in the summer.  For example the thermostat in our bedroom is located just above the furnace register so in winter we have to compensate by setting the temperature higher if we want the back to stay warm.  Our sensor in the living area is located just inches from an exterior wall, the slide out and a giant window combined with the fact it’s at eye height; so in summer the temperature here reads 5+ degrees warmer at the sensor than in the kitchen area.

Keeping the RV Cool

To rapidly cool the living area on hot days try closing all the vents in the bedroom, opening the vents on the front A/C along with all the vents in the living area, shut the door to the back area of the RV and crank up both A/C units.  Having the rear vents closed will force most of the cold air into the larger part of the coach and help it cool down quickly.  If necessary close all the shades, especially if the sun is coming in the driver’s area.  Of course you may need to do the “power shuffle” if you’re connected to 30a shore power!

When driving an RV in the Summer the heat can be a beast!  The built in HVAC for the cab is nowhere near strong enough to cool the entire RV, so when you’re driving in extreme heat it may be necessary to run the generator to power the living area A/C to cool down the RV.  I’ve even had RVers tell me that running the generator to power the roof A/C is more fuel efficient than running the cab A/C, although I haven’t done any extensive testing of this theory myself.  We have driven through the desert a few times in the summer and I know it sounds ridiculous but sometimes you really need to run both A/C units to survive the heat coming in through the giant windshield, this was especially an issue with our first 2 Front Engine Diesel RVs.  While driving the Excursion in warmer months we try and keep the bedroom door closed, and all the rear A/C vents closed, because the rear engine diesel leaks a lot of heat into the back of the RV.  If we were in a gas coach that heat would be up front by our feet, so this is where a rear engine diesel comes in handy.  However in the winter it’s the opposite. (see our post on diesel vs gas here)

how to work rv thermostat

A few things I have learned (the hard way):

1. Our first class A RV was 31 feet and only had one 15,000 btu A/C unit.  I remember sitting at the lake in Dallas, with the temperatures soaring into the triple digits…that A/C ran non-stop and the temperature inside the RV never cooled below 94 degrees.  One A/C unit is not enough to cool a 28’ or larger RV in high temps, you need two A/C’s!

2. If you want to capture the condensation water from the A/C unit it is possible to distill the water or at least kill the bacteria with a Camelbak All-Clear type of device.  I am mentioning this because I keep getting asked and I’m not sure why, my opinion is if you’re running the A/C enough to produce that much water then you’re not really worried about conserving energy so why bother capturing a few ounces of water?

3.  A Tree is your friend!  If you can find a spot by even one small tree you can drastically reduce the heat inside your RV.  Try to find a tree to block the windshield or the driver’s side of the RV, and put out your awning to cast as much shade around the RV as possible.

4.  If you’re trying to Wild Camp in hot temperatures then you’re in for a real battle!  Trees are good for temperatures but bad for solar, this is where a portable solar kit may come in handy.  You could also create an evaporative swamp cooler and install a couple of (amazon link so you can see what I am talking about) MaxxFan With Remote Control powered vents that have the “auto” temperature setting so they open and close as the temperature changes inside the RV.

5. Do not run the dash A/C when climbing giant hills, or mountains, in the desert…you can overheat the engine!  If it’s “Hotter than Hades” and you see a mountain in the distance, turn off the cab A/C, crank on the generator and run the roof A/C…or you can always turn it all off and suffer through.

Keeping the RV Warm

Furnace – We rarely use the furnace because it burns through propane like it’s going out of style.  The two instances where we most use the furnace: 1. During Wild Camping in cold temps we sometimes kick it on for a few minutes to warm up the coach in the morning, but mainly we use it to warm up the bathroom area just before taking a shower, ’cause nothings worse than stepping out of a ‘navy’ shower into a 40 degree bathroom.  2. If the temperatures are near or below freezing we’ll set the furnace temperature to 50 degrees so the RV doesn’t freeze.  If you plan on RVing in freezing temps make sure you have a full tank of propane and watch our videos on How to Prepare an RV for Winter Camping.

Heat Pump – The heat pump is built into the AC and works great if you use it correctly.  From my experience and mistakes I’ve learned a lot about this little heat pump:

1. The Heat Pump does not work when temperatures are below 45 degrees.

2. Do not attempt to run the heat pump when plugged into a 20a outlet, use the heat pump when you’re plugged into a 30a or 50a plug.

3.  Cranking the thermostat way up when using the heat pump will cause the propane furnace to kick in, now you’re wasting propane and using electricity which is pointless (unless your goal is to heat up the RV as quickly as possible).  Many thermostats are setup so both the furnace and the heat pump kick on when you select a temperature that is more than 5 degrees higher than the current temperature.  When heating the RV with the heat pump I increase the temperature setting in 4 degree increments, which keeps the propane furnace from ever kicking on.

I haven’t found any RV Climate Control system that I think is perfect, however with a little tweaking, a little extra knowledge, and some insights from your favorite mistake maker (that’s me), keeping the RV comfortable is a breeze (haha, funny right?).

Share your thoughts and expertise in the comments below, and if you’ve had experience with a swamp cooler or any scientific evidence of running the rooftop A/C while driving we’d love to hear about it.

Disclaimer – Fleetwood commissioned the above video for their website as a part of an educational segment called RV Quick Tips with the Wynn’s. We think it is great Fleetwood wants to educate their customers, but as always our opinions and experiences are our own and cannot be purchased.

Famous for my "how-not-to" videos, and typically the man behind the camera, sometimes I’m forced to be here in the “spotlight”. When you see my face you’re probably reading something more technical than adventurous, but either way I do my best to tell it like it is and infuse my opinions into the commentary…after all this is a blog and not MSN.

Comments (63)

  • Ric

    I have a Rockwood a frame type RV 20 feet as of an Arizona the temperature today was so hundred and eleven the air temperature coming out of my heat pump was mid-sixties to high 60s is that right or should it be cooler than that I couldn’t get the RV to be lower than 100 degrees maybe 99 degrees please help

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    • Curious Minion

      Hey Ric. The problem probably isn’t with your AC – it’s that most RVs have very poor insulation and no matter what you do the AC won’t be able to keep up with Arizona temps and sun beating on the roof. You can purchase RVs that are “winterized” with much better insulation and double-paned windows, both of which also help with cooling. Northwood even makes a Desert Fox line for warm weather camping. You can try using Reflectix in all of your windows and skylights, and the Wynns made a video with other cooling tips from their experience in the Nevada desert: https://www.gonewiththewynns.com/keep-cool-extreme-heat-ideas-burning-man Hope that helps!

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  • Kaye Grimes

    Do I need to close off the roof AC vents while I’m running the heat furnace which come out of floor will it keep the heat in if I did close it off

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    • Maurice Kenner

      I wondered about the same issue. Only the rear of my 5th wheel heats up.

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  • Linda kujawa

    New 32 ‘ 5th wheel with 2 ac. After 64 days in Texas heat. Front ac stopped working. Rear w heat pump ac. Froze up. Coleman. Who should pay for our stay at motel while new units being replaced ??

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    • Curious Minion

      Unless you have a really good comprehensive warranty from the dealer that will cover it, I’m afraid it’s probably you. Just like if your car broke down and needed to be at the dealer for a week – they will only pay for a rental under certain circumstances. Hope it’s done soon and fixes the problem!

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  • When plugged in to shore power we never use the propane furnace. In fact it stays off except to heat the bays in sub freezing temps when traveling or dry camping. Our 20 year old Mountain Aire is well insulated so two 1500W space heaters keep the coach toasty down to freezing. At 30 degrees we turn on two more space heaters in the bays to keep the water liquid. We’re comfy to well below zero (I know a bit about winter camping as I spend the worst SD winter in 100 years in a Gulf Stream 29 ft trailer 20 years ago). Our coach has heat strips in both A/Cs but the space heaters are less noisy. Heat pumps will be purchased if we ever have to replace an A/C unit.

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    • Pork

      We do the same 2 1500 what ceramic heaters and 2 lasko myheat 100 watt ceramic heaters in fresh water bay and one in black and gray bay. What do you use in your bays? We have a Monaco dp with dual pane windows. Nice and toasty. If it gets to cold we get are Kimberly wood stove going. 😉

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    • Jim

      97 winter?

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  • Nicole

    You have to be carefully about RV roof. Don’t let it leaking do ac immediately and RV Roof Leaks Repair is kind of solution that makes your roof energy efficient.

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  • Stephanie Mitchell

    I turned the thermostat to furnace and the celling air came on tonight. We have turned on the furnace before and it blew heat out of the floor. Why now is it not coming through the floor and why is the air coming on?

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    • Nick manning

      Sounds like your number 2 AC is not turned off.

      reply
  • Jerry Cartier

    Can I run my rv heater with the AC cover on?

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  • Sheila farrell

    Do you needx your water on to run your ac n my ac leaks water what can it be they say the drain pan might be cloted but i dont know to unclog it help

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  • Ivin Boren

    To emily Its best to open windows quickly go outside and wait as hot air escapes for about 10 MINUTES. Close windows and turn on cooling system(s) quickly go outside again for another 10 MINUTES . Look at the interior temp. then decide if its healthy to stay inside. The more shade is better. Spray the RV with water or tarp over it…

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  • I know the technologies are different, but why is it that you can put a $100 window air conditioner in a bedroom at home, and on the warmest day of the year, darn near make ice cubes in there, but an expensive roof AC on your RV can only handle about 15 degrees less than the outside temp? Reading your reader responses, someone mentioned putting a “portable ac” in place and maintaining 78 degrees, wonder if they were actually using a small residential window air conditioner. Our 1993 Fleetwood Flair has a 2″ roof, and I blogged about trying to keep cool a couple of summers ago here: http://www.mytripjournal.com/travel-788232-heat-index-senior-citizens-television-weather-afternoon-air

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  • Tracy Parsons

    I am keeping mine running my AC unit approx 10 degrees below outside temp. It seems to cycle on and off like every minute. Is it better to just keep it at a cooler level than try to conserve a bit? I don’t know if the power surge from going on and off is worse than just letting it run!
    Help!
    I have a Coleman camper and am not real sure about my AC. Sounds silly I know but I have read the owners manual cover to cover and all I get is” refer to manufacturer website for further details. ”
    When I go on line…all I get are ads !
    Help!

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  • katherine

    as mr rogers said wont you be my neighbor lol wow we could sure use your brain sometimes to figure this all out …. weare both 50 and prety darn new to RVing so when they say you cant teach an old dog new tricks i beg to differ 😛

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  • First off I want to say THANK YOU for all the amazing information on this website! My husband and I are preparing to move into an RV full time and we were having such a hard time finding good information that when I found this website I almost cried! Anyways, we will be living in north Missouri and the winters can get pretty rough, and we are concerned about excessive propane usage ($$$). I noticed in this post you said you rarely use the furnace and in another post you said you liked the heat/cool fan (can’t remember the brand right now but I’m sure you know what I’m talking about). Do you find that is enough to heat your RV and that’s why you don’t use the propane or do you just bundle up and stick the cold weather out? Thank you!!

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  • phillip rollman

    i am building my own rv and wonder do your black and grey water tanks have some sort of tank heater?

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  • Jamie holt

    I have a question. Have you guys ever left your RV for a few days during freezing weather? If so, how did you handle it? Did you antifreeze? Did you leave the heat on?

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  • turned my warm heating on today it ran for a thew minutes then cut out one I can’t get it to come back on I had my thermostat set at 20c can’t find any fuses and my gas bottle is full any ideas please?. Thank you.

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  • Thomas

    The only way I have been able to tolerate the desert heat and RV life was by purchasing a portable a/c unit that I vent out the window. Camping in AZ along the river in 115 degree heat, my portable A/C unit running in my coach can maintain a comfortable 78 degrees inside. Keeping the coach cooler helps preserve everything inside also. Before purchasing my portable a/c my refrigerator could not keep my food cold in extreme temperature. I can now enjoy the desert, the river and my RV.

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  • Great informational video. Nice tips, and isn’t it interesting what we learn the hard way!

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  • Emily

    In triple digit heat, and you are not in the rv most of the day, is it best to close all the Windows, turn A/C on and set the thermostat, or leave Windows open, A/C off and cool it down when you get back to the RV?

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  • Bill

    One thing to consider would be putting lumar tinted window coverings on your windshield. This will significantly reduce the heat that can be transmitted through your windshield. You should also turn the other windows in the motorhome including the side windows. This not only reduces heat transmission but it also totally stops UV rays from getting inside and damaging your skin and the interior of your motorhome.

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  • Skinny Badger

    Keeping your air conditioner filters clean on the inside and the fins on the outside free of debri and wasp nests will also help to keep your the unit running efficiently and cold. Of course, I learned these things the hard way. If you have trouble getting cold air, check these culprits first. It’s usually a simple fix unless you get stung. :-}

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  • Jim Loeks

    Hi Jason, Big Fan! Thanks…. We are serious motorhome shoppers and love the 33-D. I would like to hear your thoughts on aqua hot. We live in the north (Michigan) ,
    love winter sports and dry camping. For a bunch of reasons, aqua hot is at the top on our must-have list. I am wondering whether Fleetwood can install aqua hot in the 33d? Best, Jim

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    • We love the hydro hot. We bought our coach in spite of the fact that it had one, and we found that we love it. A properly maintained hydro hot doesn’t make that much noise, and if you open your grey tank, you can stand in a hot shower until your skin peels off. The burning of diesel hasn’t been an issue for us. We stay put 5 months out of the year, and I don’t think it uses a quarter of a tank for hydro hot and for zone heating. It all comes down to personal preference, but we would not go back to propane.

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  • Michael Bolton

    Hello,hello,hello!! So I was watching the Travel Chanel and a program called MEGA R.V. and low and behold who do I see.? Why it’s the WYNN’S, number 5 on the count down, ( I would have made ya’s #1) For the life of me I don’t understand why you two don’t have a show on their chanel?? I mean they have people going around the country eating food at different greasy spoons and you people eat alot healthier than that. I’m not meaning too denigrate those programs, just saying you should have one also. But alas all the production would take the “FUN” out of what you do I suppose. Keep-up the good work……Mike

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  • James Blair

    Not all thermostats, including the RV Comfort, will turn the furnace on automatically when using the heat pump. Though more common in fifth wheels and trailers if you have a two stage furnace it will not do so. Easy to tell though as you will have two thermostats, which should be an important clue. One for the A/C and heat pump and one for the furnace.

    Also we paid the extra to have a heat pump in both A/C for 40′ fifth wheel Money well spent and I highly recommend. We are able to use ours down to 38 degrees and even lower in a few cases. It depends on the humidity.

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  • I found this amperage/watts table with a quick Google search.

    fltailgators.com/resources/RV+Appliances+Power+Consumption.pdf

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  • Phil Bruce:
    “Power shuffle” is managing what’s turned on to stay below [the max. requirement of a breaker]? <= Yes.

    "We have a single AC unit and I thought that two AC units would require 50A." <= 50A is VERY large for A/C's!! As Jason said, "…we just know how much each device pulls so we understand what can run simultaneously." Each "device" has a required "pull" actually a power requirement (Watts). This is posted somewhere on the device in a tag.

    Add the watts for the A/C's. If it exceeds the breaker amount (Amps) by the formula below, you can't turn both on simultaneously or you'll trip the breaker (OR YOU'LL CAUSE A FIRE IF THE BREAKER'S DEFECTIVE).

    P = VI (Ohm's law)
    P = Power (Watts)
    V = Voltage (120V)
    I = Amperage (Amps)
    I = P/V = 540W / 120V = 4.5A
    If the breaker's 10A, you're Ok.

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  • David Lee:
    “Do the roof air conditioner units in RVs use inside air as the air intake to cool, or do they use outside air?” <= I believe most use the "recycled / recirculate / inside air" air as a default mode & not fresh air intake for "efficiency." If they used "fresh air," the A/C would not be as efficient in its operation.

    However, an A/C having a setting allowing the capability for "fresh air" intake would allow for an exchange of the interior air with the outside air. But make sure you're aware of being in this mode. Otherwise you'll be paying for essentially attempting to 'cool the neighborhood' instead of just your RV / mobile Tiny House (THm). dCb

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  • Thanks for pointing out the 5-degree ambient temperature difference triggering the furnace! We recently had our first cold night, and used our heat for the first time. I set our thermostat to “Heat Pump”, but the furnace came on. Now I know why! I probably had the thermostat set to 65 degrees and it was 55 in the coach. Next time we’ll try a gentler ramp up and see if we can keep the furnace off.

    -Mike

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  • Jason,
    First I’ve seen of remote temperature sensors. Fantastic!!
    Don’t have to have the thermostat strategically located and even then it may not be ‘just there’ for controlling the temperature where it’s needed – i.e., the bedroom, especially. dCb

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  • Jason,
    As usual, thanks for the post. A great article as I once owned an HVAC company.
    I prefer a split HVAC system for RV’s or TH’s – an A/C with a propane furnace.
    TH’s allow for ceiling fans to COMPLETELY circulate the air – keep it in the winter mode on medium speed 24/7 and that A/C won’t run 24/7 churning up your electricity bill. dCb

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  • Glenda Kelsey

    We were freezing in our 25′ travel trailer until a friend loaned us a small oil-filled, roll around radiator that plugs into shore power. It has a variable thermostat with three settings. Since we couldn’t leave a space heater on all night, this was a great alternative that kept us nice and toasty all winter. We loved it so much we bought our own and use it in our larger 35′ motor home. The furnace will still kick on, but shuts off sooner when we use the “radiator”!

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  • Jason/Nikki,

    Do you have a link to a set of amperage draw tables for doing the “Power Shuffle” you mentioned.

    Thanks,

    Don and Carol

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  • David Lee

    Jason, I don’t have a 5th wheel yet, but maybe you can answer this question: Do the roof air conditioner units in RVs use inside air as the air intake to cool, or do they use outside air? That would make a huge difference as to how much you could cool your rig. I know home air conditioners use inside air. The normal temperature difference on them is 15 to 20 degrees between the vent and the intake. Thanks for all the info you and Nikki provide.

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  • Tim Fitch

    Jason,
    Thanks for the practical advice. I had a 38′ sailboat with air, ( connected to shore power). I could manage to keep it 10 to 12 degrees cooler than the outside temp in the South Florida sun.

    Tim

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  • Phil Bruce

    “Power shuffle” is managing what’s turned on to stay below 30A (e.g. AC units, microwaves, hair dryers, etc.)? We have a single AC unit and I thought that two AC units would require 50A.

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  • Chip Osborn

    I own a Leisure Travel Serenity. Love it. Just returned to Kansas City from a 33 day 5,300 mile Canada/US trip. The Serenity carries a low profile Dometic 15,000 BTU AC unit. When using the heat pump function, with temperatures above 45 degrees, the unit pumps moisture into the coach. It fogs the windows, puts moisture on all surfaces (walls, countertops, seats, electronics) and registered 90+% humidity on our inside temperature/humidity gauge. Eventually, the moisture dissipates, but not for 15 to 20 minutes. Too long to be comfortible. Have you had this experience?

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  • Hi guys!

    Thanks for the video and the tips.

    Our cats love to sit on the dashboard and look out the windows, to the point that they’ll shove the privacy curtain out of the way. So at night we leave a gap in the center for them to use and have created a second curtain that sits at the back of the dash to keep our privacy.

    When we’re traveling in hot weather, we take that same curtain and hang it ( we added some small hooks ) behind the driver and passenger seats. This keeps the cool air from the engine A/C contained up front and lets the back of the RV heat up.

    When watching the engine temperature increase when climbing grades, I’ve felt that the dash gauges leave something to be desired. So I’ve added a Scangauge II to the dash, plugged into the OBD2 port. It’s programmed to show me coolant temp, transmission temp, fuel mixture ( gas only ) and voltage. Any change in those can be an early warning of problems that the original gauges and lights may not tell me.

    Safe Travels!

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  • Mary

    Good information. Not an RV owner yet however I am filing all this good info for later years.

    reply

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