Newbie Question: Motorhome in the Heat

[Scubawise]

Originally Posted by txc2936@yahoo.com

Only thing i noticed stepping up to the THOR ACE and FORD 53 chassis,. We owned the Chevy Freedom Elite and the Chevy blew ice cubes. Seems like the F53 doesn't have the cooling output the Chevy does. i can put a thermometer at outlet see if its close to 57Deg F.

With our TT and a 2015 hyundai Santa fe..it was too cold..we never used high even in Arizona.

Our Thor vegas is too cold so we use lower setting when driving

[DavidEM]

I just spent three nights in an RV park in eastern NC, near the coast. We had shade in the morning, but by noon we had full sun on our newish Axis 24.1 all afternoon. The high temps were in the mid 80s.

The A/C handled it well until late afternoon when the front of the cabin got a little hot- in the low 80s. The aft sleeping cabin was cool though- in the mid to upper 70s. The A/C compressor ran continuously from about noon until 8:00 PM. All in all it wasn't too bad. The sunshade was pulled down to block the sun from that enormous windshield also helped.

I was a little surprised at how well the absorption fridge handled the afternoon temps, particularly the sun in the afternoon which was directly on the side with the fridge. It stayed at near zero in the freezer and about 40 in the fridge which were its normal set points.

I can see though how the A/C just wouldn't keep up with temps in the nineties combined with full sun. Running the chassis cab A/C is one way to deal with high daytime temps, but probably isn't good for the engine or the environment.

David

[The Gritz Carlton]

Originally Posted by LarryD

Not positive but I thought they were 13k. I'd "upgrade" to the largest possible without having to cut or modify. From the very little research I've done the stock units are neither the largest nor "best" in class that would seem to fit with nearly zero effort. I'll do another summer with them before making a decision.

Pretty sure they are 15's. All rooftop models fit the standard 14" square hole. Maybe pull inside covers off and check for blockage, etc. You're the first I heard having cooling issues with a Super C.

[Scubawise]

Originally Posted by DavidEM

I just spent three nights in an RV park in eastern NC, near the coast. We had shade in the morning, but by noon we had full sun on our newish Axis 24.1 all afternoon. The high temps were in the mid 80s.

The A/C handled it well until late afternoon when the front of the cabin got a little hot- in the low 80s. The aft sleeping cabin was cool though- in the mid to upper 70s. The A/C compressor ran continuously from about noon until 8:00 PM. All in all it wasn't too bad. The sunshade was pulled down to block the sun from that enormous windshield also helped.

** use the sun shade to only block the sun side and have great outside light

I was a little surprised at how well the absorption fridge handled the afternoon temps, particularly the sun in the afternoon which was directly on the side with the fridge. It stayed at near zero in the freezer and about 40 in the fridge which were its normal set points.

Fridge will work when 120 degrees..just cool before trip..any NEVER put anything warm in!

I can see though how the A/C just wouldn't keep up with temps in the nineties combined with full sun. Running the chassis cab A/C is one way to deal with high daytime temps, but probably isn't good for the engine or the environment.

*** Stop run the dash cabin all dam A/C you can!!!
If WIFE ETC haply trust me do it

David

I just spent three nights in an RV park in eastern NC, near the coast. We had shade in the morning, but by noon we had full sun on our newish Axis 24.1 all afternoon. The high temps were in the mid 80s.

*** Just cool starting 6am

The A/C handled it well until late afternoon when the front of the cabin got a little hot- in the low 80s. The aft sleeping cabin was cool though- in the mid to upper 70s. The A/C compressor ran continuously from about noon until 8:00 PM. All in all it wasn't too bad. The sunshade pulled down to block the sun from that enormous windshield also helped.

*** Sunshade on sun windows

I was a little surprised at how well the absorption fridge handled the afternoon temps, particularly the sun in the afternoon which was directly on the side with the fridge. It stayed at near zero in the freezer and about 40 in the fridge which were its normal set points.

*** Best Fridge keep cool nothing warm

I can see though how the A/C just wouldn't keep up with temps in the nineties. Running the chassis cab A/C is one way to deal with high daytime temps, but probably isn't good for the engine or the environment.

*** keep your setup

[Hugh.vines@att.net]

Last year I was having real heat problems in my axis one unit ac. I pulled top cover pushed towel in hole sprayed all coils with ac cleaner used two bottles but ver clean when finished. Then I bought that air conditioner styrofoam thing off the internet installed. Then pulled all vents that led to the end of duct and stuffed with cotton insulation so air could not pass vent. That was probably the best cure itself. I then switched to digital thermostat. Now you can hang meat in that baby no matter what the temperature is outside.

[raffaelli]

Originally Posted by nwood488

Hello,

We just bought a 2016 Thor Majestic 23A recently and will be driving across country with our family as we move from the West Coast back to the South. One of our stops is going to be in the Phoenix area for a couple days.

Obviously, we have a working AC in the coach. I am just concerned with the 100-102 heat and what that is going to be like if we don't have any other source of air conditioning.

What should we expect? Should we get a portable AC?

Any suggestions are appreciated!

My understanding is the AC will be able to maintain about 20 degrees less that what is it outside.

[JimOIB]

Lots of good info on the Forum on how to “tune-up” your A/C - worth searching for.

Lots of good practical advice given in this thread as well.

Here is my $.02 that applies to cooling and heating the coach.

1. 2nd law of thermodynamics - heat flows spontaneously from a hot to a cold body. Given that, you need to look at places where this will happen. In my coach (class c with full wall slide) the slide is the biggest culprit. Where the slide and the coach floor meet is a big heat/cool loss with nothing on in the coach. The wiper seals under the slide have too many places that don’t seal well - where seals meet horizontal/vertical, the utility gap, and the safety hold downs. Turn on the A/C or furnace and hot/cold air is drawn into the coach when you don’t want it to. DW made a custom set of draft dodgers that we seal the gap with and I use a cutoff pool noodle to fill the utility gap. Simple foam pipe insulation from box HW store will work too.

2. HVAC is for the comfort of humans/pets. Don’t heat or cool an area that doesn’t have a human in it. We keep cabover curtains closed and the 2 A/C outlets closed as to not condition that space. We also have a curtain between the cab and coach so we don’t condition the cab.

3. Design flaw - If you have ducted A/C and an inside A/C cover with two A/C outlets then you have what I call a design flaw from the OEM of the coach. There are two styles A/C covers, one for duct and one for ductless. Ductless is for use in a small RV, duct for a large. Using a ductless cover is a ducted system will disrupt airflow/cooling capacity. I replaced-my A/C cover with a duct model.

4. Cover the front widow if you can. I use an Element windshield bra - you’d be amazed at the heat gain/loss in the cab due to thermal radiation.

As far as shortening the end of the A/C duct like many suggest, I’m not onboard with that. When we put the mechanical in our brewery all of the runs were about 6-8 inches longer than needed - the HVAC registers were not at the very end of the run - these were metal not flexible runs. I asked the tech why and he stated that there needs to be some turbulence at the end of the run to get the desired airflow from the register. I did a simple “ fountain of all knowledge” check and his statement seemed reasonable.

[16ACE27]

Originally Posted by jimbo12

As far as shortening the end of the A/C duct like many suggest, I’m not onboard with that. When we put the mechanical in our brewery all of the runs were about 6-8 inches longer than needed - the HVAC registers were not at the very end of the run - these were metal not flexible runs. I asked the tech why and he stated that there needs to be some turbulence at the end of the run to get the desired airflow from the register. I did a simple “ fountain of all knowledge” check and his statement seemed reasonable.

Doesn't pass the smell test to me. The flow all the way down the register is turbulent. There would be no flow in the dead head except for leakage out of the register which is what is stopped by closing off the dead head.

[JimOIB]

Originally Posted by 16ACE27

Doesn't pass the smell test to me. The flow all the way down the register is turbulent. There would be no flow in the dead head except for leakage out of the register which is what is stopped by closing off the dead head.

You are correct - I looked at my notes and it was explained as static pressure and not turbulence. As explained, the extra plenum length helps maintain a static pressure allowing registers to have equal air flow. A register directly on the end of the plenum will rob the others of air flow. Still might not pass the smell test…

[16ACE27]

Originally Posted by jimbo12

You are correct - I looked at my notes and it was explained as static pressure and not turbulence. As explained, the extra plenum length helps maintain a static pressure allowing registers to have equal air flow. A register directly on the end of the plenum will rob the others of air flow. Still might not pass the smell test…

Pascal's law says the pressure in the dead head will be the same as the pressure in the register with moving air. And in fact, the pressure closest to the fan will be higher than the pressure near the end of the run due to head loss in the register, so outlets closer to the fan get more air flow than the outlet at the endo of the line which passes the everyday experience test whether it's air in A/C registers or multiple sprinklers daisy chained on a length of garden hose.

Regardless, the MAIN reason for closing off that dead area in our RVs is to stop the air flow leaks to the front and/or rear caps and other nether regions.

[Travelin' Texans]

Originally Posted by Scubawise

We open all windows and vents early morning..run maxair to pull cool air..then A/C UP

That would work IF it cooled down at night! Summer in Arizona you better not open the windows as it doesn't cool down til about an hour before sunrise then by 7am it's already HOT!

[Travelin' Texans]

Originally Posted by raffaelli

My understanding is the AC will be able to maintain about 20 degrees less that what is it outside.

IIRC the rule is the cooled air existing the A/C should be 20 degrees cooler than the ambient temperature inside not that the coach itself should be that cold.

[JimOIB]

Originally Posted by 16ACE27

Pascal's law says the pressure in the dead head will be the same as the pressure in the register with moving air. And in fact, the pressure closest to the fan will be higher than the pressure near the end of the run due to head loss in the register, so outlets closer to the fan get more air flow than the outlet at the endo of the line which passes the everyday experience test whether it's air in A/C registers or multiple sprinklers daisy chained on a length of garden hose.

Regardless, the MAIN reason for closing off that dead area in our RVs is to stop the air flow leaks to the front and/or rear caps and other nether regions.

Air flow leaks - got it. I have 3 air flow leaks in one duct that I found one night - OEM installed overhead lights in the supply duct. A/C vents open, DW turns on lights and the vents glowed. Can’t make this stuff up.

Pascal’s law…I was thinking more Bernoulli’s principle ;-)

[Hot in AZ]

Originally Posted by nwood488

Hello,

We just bought a 2016 Thor Majestic 23A recently and will be driving across country with our family as we move from the West Coast back to the South. One of our stops is going to be in the Phoenix area for a couple days.

Obviously, we have a working AC in the coach. I am just concerned with the 100-102 heat and what that is going to be like if we don't have any other source of air conditioning.

What should we expect? Should we get a portable AC?

Any suggestions are appreciated!

Hi, Having lived in the Phoenix area for 25 years, I can tell you that in July and August, the night time temps can be in the high 80's or above, and daytime temps 108-114 are common. Look for a shady camp site. I don't know about a portable AC, but we did use fans as well as our motor home AC. It was still uncomfortably warm. We run our generator and coach AC when on the road in high temperatures as well as the cab AC. Be aware that when gas tank gets down to about 1/4 full, the generator will shut down. Good luck.

[cgeace29.3]

Phoenix in the end of may can easily reach 110 - 115 degrees. Your M H is a fiberglass box and may cool down to 90 - 95 degrees, about 20 degrees of cooling is what you will get.
I would seriously consider I 40 through flagstaff and not I 10 or I 8.
Ben there done that.

[mikebreeze]

I have a 2006 Thor Four Winds Majestic 23A. When traveling the Ford air conditioning does very well. While stationary the RV air conditioning usually keeps the interior of the RV 15-20 degrees cooler. However, once the temp goes over 100 degrees all bets are off. Make sure that you park under trees, shut all the curtains in the rig, get one of those windshield sun shades and buy some Reflectix. Place the sunshade in the front window. Cut the Reflectix to the shape of all of your windows, including the driver and passenger side windows and the vents and place the pieces between the curtains and the glass. Also close the curtains to the attic as well as the curtain between the cab and the RV portion of your rig. I have had my rig in 105 degree outdoor temps and the interior has been around 75. I've had my rig for 10 years now and have perfected this method.

[LarryD]

So along the lines of solutions here. Has any one with a super C found a decent windshield cover for their rig? I use:

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

which honestly fits like poop 'cause its designed for the E series. Gets the job done though while I try to find a better option.

Anyone know of one?

[knucklehead]

Originally Posted by nwood488

Hello,

We just bought a 2016 Thor Majestic 23A recently and will be driving across country with our family as we move from the West Coast back to the South. One of our stops is going to be in the Phoenix area for a couple days.

Obviously, we have a working AC in the coach. I am just concerned with the 100-102 heat and what that is going to be like if we don't have any other source of air conditioning.

What should we expect? Should we get a portable AC?

Any suggestions are appreciated!

Understand that the BEST A/C in a RV will only make a difference of 20 degree's from the outside temps. Use only at night if possible because running it 24/7 is not a good idea. Use the fans to pull hot air out before to start your A/C. Good luck!!!

[Pete'sMH]

Originally Posted by knucklehead

Understand that the BEST A/C in a RV will only make a difference of 20 degree's from the outside temps. Use only at night if possible because running it 24/7 is not a good idea. Use the fans to pull hot air out before to start your A/C. Good luck!!!

Why is running 24/7 not a good idea? I certainly haven’t had any problems doing it on toasty days.

[JimOIB]

Two other items I’d like to add to my previous post.

1. The seals on the coach door compress over time and cause drafts. I just replaced mine and air flow in/out greatly dropped.

2. A clean A/C up top is important. Since this is a new to you coach and you don’t know where it has been then clean everything under the shroud. Lots of YouTube videos on this. Dirty coil or evaporator fins can greatly reduce cooling capacity. Also check any pipe insulation if there is any - replace it if it is cracked or torn.