Good Sam Club Open Roads Forum: Do you run house AC while on the road
Open Roads Forum Already a member? Login here.   If not, Register Today!  |  Help

Newest  |  Active  |  Popular  |  RVing FAQ Forum Rules  |  Forum Posting Help and Support  |  Contact  

Search:   Advanced Search

Search only in Class A Motorhomes

Open Roads Forum  >  Class A Motorhomes  >  All

 > Do you run house AC while on the road

Reply to Topic  |  Subscribe  |  Print Topic  |  Post New Topic  | 
Page of 5  
Prev  |  Next
Rick Jay

Greater Springfield area, MA

Senior Member

Joined: 02/02/2003

View Profile


Online
Posted: 05/31/21 12:33pm Link  |  Quote  |  Print  |  Notify Moderator

Lwiddis wrote:

Rent an A before you buy. That “fishbowl” driving compartment may freak you out. Advantage of a C or a truck camper is the shady overhang.


Interesting point and while I guess that can be true, the VIEW out that "fishbowl" is often well worth any slight added inconvenience all that glass might present. It's an issue which didn't bother any of us. The kids LOVE sitting up front when we travel. LOL...dang...it just hit me...next time we go out...THEY'RE going to be able to DRIVE!!! Yikes!!! But I digress....

To be honest, I think what DW had the hardest time adapting to, was how much closer the passenger side of the rig is to the edge of the road when traveling down some winding country back roads. My wife commented "I think we're closer to the mailboxes than the mailman gets!" LOL

Granted, a Class C can be just as wide, but the cab part is a bit narrower, so there is a bit of an "extra cushion" of space between the passenger's position in the cab. This is probably an additional comfort to the passenger. And you're usually sitting much lower & closer to the road in a Class C, as well, so it's more "car-like".

~Rick


2005 Georgie Boy Cruise Master 3625 DS on a Workhorse W-22
Rick, Gail, 1 girl (24-Angel since 2008), 1 girl (20), 2 boys (21 & 18).
2001 Honda Odyssey, Demco Aluminator tow bar & tow plate, SMI Silent Partner brake controller.


JaxDad

Greater Toronto Area

Senior Member

Joined: 08/02/2011

View Profile



Good Sam RV Club Member

Offline
Posted: 06/01/21 05:48am Link  |  Quote  |  Print  |  Notify Moderator

I guess neither of my motorhomes listened to the experts, both can stay more than cool enough with just the dash A/C.

Mind you, I do understand their limitations and help them a little. Don’t try to block of the cab, that makes it worse, open the rearmost roof vent.

The weak part of dash A/C is not the cooling capacity, a Ford dash unit has more than double the cooling capacity of a rooftop unit, it’s the fan, it’s horrendously undersized.

By opening the rearmost roof vent you create a vacuum at the back of the coach which pulls the cold air to the rear for you.

dougrainer

Carrolton, Texas

Senior Member

Joined: 06/11/2007

View Profile


Offline
Posted: 06/01/21 06:33am Link  |  Quote  |  Print  |  Notify Moderator

JaxDad wrote:

I guess neither of my motorhomes listened to the experts, both can stay more than cool enough with just the dash A/C.

Mind you, I do understand their limitations and help them a little. Don’t try to block of the cab, that makes it worse, open the rearmost roof vent.

The weak part of dash A/C is not the cooling capacity, a Ford dash unit has more than double the cooling capacity of a rooftop unit, it’s the fan, it’s horrendously undersized.

By opening the rearmost roof vent you create a vacuum at the back of the coach which pulls the cold air to the rear for you.


If your statement about Ford is true, then why does Ford and Chevy option a REAR AC cooling system and control on Suburbans and Expeditions family SUV/Truck?????? I don't listen to experts, I AM one. I base my comments on 42 years as both a RV service Tech and USING both Class A and C's in 90 plus Texas heat for those 42 years. Doug

dodge guy

Bartlett IL

Senior Member

Joined: 03/23/2004

View Profile


Offline
Posted: 06/01/21 08:44am Link  |  Quote  |  Print  |  Notify Moderator

JaxDad wrote:

I guess neither of my motorhomes listened to the experts, both can stay more than cool enough with just the dash A/C.

Mind you, I do understand their limitations and help them a little. Don’t try to block of the cab, that makes it worse, open the rearmost roof vent.

The weak part of dash A/C is not the cooling capacity, a Ford dash unit has more than double the cooling capacity of a rooftop unit, it’s the fan, it’s horrendously undersized.

By opening the rearmost roof vent you create a vacuum at the back of the coach which pulls the cold air to the rear for you.


Yes factory AC will be better than the dash AC put in class A’s. But a class C is smaller and has a small driving area so yes it will feel cooler. Now.......
A class A down south in 90+ degree weather will laugh at any dash AC! And if you have kids or a wife/husband in the back you will need to run the generator and house AC.


Wife Kim
Son Brandon 17yrs
Daughter Marissa 16yrs
Dog Bailey

12 Forest River Georgetown 350TS Hellwig sway bars, BlueOx TrueCenter stabilizer

13 Ford Explorer Roadmaster Stowmaster 5000, VIP Tow>
A bad day camping is
better than a good day at work!


way2roll

Wilmington NC

Senior Member

Joined: 10/05/2018

View Profile


Offline
Posted: 06/01/21 09:22am Link  |  Quote  |  Print  |  Notify Moderator

Interesting how every time this topic comes up how much of a debate it becomes.

The answer is simple; if you get hot, you have an onboard generator that can run the rooftop airs. That's one of the reasons you have it. If you can get by with the dash air, do that. Do what makes you comfortable. You have options. After all, it's a rolling apartment with all the same amenities.


2020 F350 STX 6.7L Turbo Diesel
2020 FR Cedar Creek Silverback 29rw

JaxDad

Greater Toronto Area

Senior Member

Joined: 08/02/2011

View Profile



Good Sam RV Club Member

Offline
Posted: 06/01/21 12:01pm Link  |  Quote  |  Print  |  Notify Moderator

dougrainer wrote:

JaxDad wrote:

I guess neither of my motorhomes listened to the experts, both can stay more than cool enough with just the dash A/C.

Mind you, I do understand their limitations and help them a little. Don’t try to block of the cab, that makes it worse, open the rearmost roof vent.

The weak part of dash A/C is not the cooling capacity, a Ford dash unit has more than double the cooling capacity of a rooftop unit, it’s the fan, it’s horrendously undersized.

By opening the rearmost roof vent you create a vacuum at the back of the coach which pulls the cold air to the rear for you.


If your statement about Ford is true, then why does Ford and Chevy option a REAR AC cooling system and control on Suburbans and Expeditions family SUV/Truck?????? I don't listen to experts, I AM one. I base my comments on 42 years as both a RV service Tech and USING both Class A and C's in 90 plus Texas heat for those 42 years. Doug


Because, as I said, the fan is the weak link, it's not a difficult concept to grasp. In order to get cool air to the back they put in a second unit so you don't have to freeze in the front to be comfy in the back.

Frankly I'm kind of surprised an expert wouldn't realize that Suburbans, Ecursions and other units with rear A/C DON'T have TWIN A/C compressors.

Why? Because the single one will provide far more cooling than required.

I DOo listen to experts, they know what they're talking about.

way2roll

Wilmington NC

Senior Member

Joined: 10/05/2018

View Profile


Offline
Posted: 06/01/21 12:25pm Link  |  Quote  |  Print  |  Notify Moderator

JaxDad wrote:

dougrainer wrote:

JaxDad wrote:

I guess neither of my motorhomes listened to the experts, both can stay more than cool enough with just the dash A/C.

Mind you, I do understand their limitations and help them a little. Don’t try to block of the cab, that makes it worse, open the rearmost roof vent.

The weak part of dash A/C is not the cooling capacity, a Ford dash unit has more than double the cooling capacity of a rooftop unit, it’s the fan, it’s horrendously undersized.

By opening the rearmost roof vent you create a vacuum at the back of the coach which pulls the cold air to the rear for you.


If your statement about Ford is true, then why does Ford and Chevy option a REAR AC cooling system and control on Suburbans and Expeditions family SUV/Truck?????? I don't listen to experts, I AM one. I base my comments on 42 years as both a RV service Tech and USING both Class A and C's in 90 plus Texas heat for those 42 years. Doug


Because, as I said, the fan is the weak link, it's not a difficult concept to grasp. In order to get cool air to the back they put in a second unit so you don't have to freeze in the front to be comfy in the back.

Frankly I'm kind of surprised an expert wouldn't realize that Suburbans, Ecursions and other units with rear A/C DON'T have TWIN A/C compressors.

Why? Because the single one will provide far more cooling than required.

I DOo listen to experts, they know what they're talking about.


Doesn't the dash AC compressor put drag on the engine thus decreasing MPG? I would think adding a second compressor would rob a good bit of power. The genset is far more efficient at producing power. I am not sure I believe the dash AC is more powerful but even if it were it's far less efficient at cooling a large space compared to the rooftop air.

JaxDad

Greater Toronto Area

Senior Member

Joined: 08/02/2011

View Profile



Good Sam RV Club Member

Offline
Posted: 06/01/21 03:02pm Link  |  Quote  |  Print  |  Notify Moderator

way2roll wrote:

JaxDad wrote:

dougrainer wrote:

JaxDad wrote:

I guess neither of my motorhomes listened to the experts, both can stay more than cool enough with just the dash A/C.

Mind you, I do understand their limitations and help them a little. Don’t try to block of the cab, that makes it worse, open the rearmost roof vent.

The weak part of dash A/C is not the cooling capacity, a Ford dash unit has more than double the cooling capacity of a rooftop unit, it’s the fan, it’s horrendously undersized.

By opening the rearmost roof vent you create a vacuum at the back of the coach which pulls the cold air to the rear for you.


If your statement about Ford is true, then why does Ford and Chevy option a REAR AC cooling system and control on Suburbans and Expeditions family SUV/Truck?????? I don't listen to experts, I AM one. I base my comments on 42 years as both a RV service Tech and USING both Class A and C's in 90 plus Texas heat for those 42 years. Doug


Because, as I said, the fan is the weak link, it's not a difficult concept to grasp. In order to get cool air to the back they put in a second unit so you don't have to freeze in the front to be comfy in the back.

Frankly I'm kind of surprised an expert wouldn't realize that Suburbans, Ecursions and other units with rear A/C DON'T have TWIN A/C compressors.

Why? Because the single one will provide far more cooling than required.

I DOo listen to experts, they know what they're talking about.


Doesn't the dash AC compressor put drag on the engine thus decreasing MPG? I would think adding a second compressor would rob a good bit of power. The genset is far more efficient at producing power. I am not sure I believe the dash AC is more powerful but even if it were it's far less efficient at cooling a large space compared to the rooftop air.


I think you’re holding that stick by the wrong there friend. An engine driven A/C compressor cycles on & off as needed so it’s only a load (decreasing MPG as you put it) when it’s actually working, the genset to run the rooftop runs continuously. BTW, studies have proven that the engine-driven A/C compressor is such a tiny load in the overal scheme of things that driving with the /C off and the windows open will actually burn more fuel than using the A/C. Again, that is mostly because A/C is an intermittent load, open windows are a constant load.

I also think you misread my post, I said there is NO second compressor running, not unless you have the rooftop running that is.

way2roll

Wilmington NC

Senior Member

Joined: 10/05/2018

View Profile


Offline
Posted: 06/01/21 03:31pm Link  |  Quote  |  Print  |  Notify Moderator

JaxDad wrote:

way2roll wrote:

JaxDad wrote:

dougrainer wrote:

JaxDad wrote:

I guess neither of my motorhomes listened to the experts, both can stay more than cool enough with just the dash A/C.

Mind you, I do understand their limitations and help them a little. Don’t try to block of the cab, that makes it worse, open the rearmost roof vent.

The weak part of dash A/C is not the cooling capacity, a Ford dash unit has more than double the cooling capacity of a rooftop unit, it’s the fan, it’s horrendously undersized.

By opening the rearmost roof vent you create a vacuum at the back of the coach which pulls the cold air to the rear for you.


If your statement about Ford is true, then why does Ford and Chevy option a REAR AC cooling system and control on Suburbans and Expeditions family SUV/Truck?????? I don't listen to experts, I AM one. I base my comments on 42 years as both a RV service Tech and USING both Class A and C's in 90 plus Texas heat for those 42 years. Doug


Because, as I said, the fan is the weak link, it's not a difficult concept to grasp. In order to get cool air to the back they put in a second unit so you don't have to freeze in the front to be comfy in the back.

Frankly I'm kind of surprised an expert wouldn't realize that Suburbans, Ecursions and other units with rear A/C DON'T have TWIN A/C compressors.

Why? Because the single one will provide far more cooling than required.

I DOo listen to experts, they know what they're talking about.


Doesn't the dash AC compressor put drag on the engine thus decreasing MPG? I would think adding a second compressor would rob a good bit of power. The genset is far more efficient at producing power. I am not sure I believe the dash AC is more powerful but even if it were it's far less efficient at cooling a large space compared to the rooftop air.


I think you’re holding that stick by the wrong there friend. An engine driven A/C compressor cycles on & off as needed so it’s only a load (decreasing MPG as you put it) when it’s actually working, the genset to run the rooftop runs continuously. BTW, studies have proven that the engine-driven A/C compressor is such a tiny load in the overal scheme of things that driving with the /C off and the windows open will actually burn more fuel than using the A/C. Again, that is mostly because A/C is an intermittent load, open windows are a constant load.

I also think you misread my post, I said there is NO second compressor running, not unless you have the rooftop running that is.


The RPM's on the gen set likewise only run high when under load as the AC cycles on and off. The studies about windows open are based on the physics of open window creating drag compared to the dash AC. Closed windows and no AC gets better mileage than with the AC- ergo, AC impacts MPG. It's not comparing the dash AC to the rooftop AC. You won't convince me that the dash AC is more efficient at cooling the coach than even one rooftop AC and likewise trying to say the MPG impact of the generator running over the dash AC is probably not even measurable. So, genset and rooftop air = a cooler coach and likely the same MPG loss as the dash air alone. At the end of the day, I wouldn't care anyway. I never measured MPG when we had our MH and don't measure it now towing a FW. Always chose the roof air over dash AC and everyone in the coach was happier about it. To each his own.

Back to the OP, do what makes you comfortable, the impact to MPG is negligible when comparing the 2. On a hot day, I doubt the dash air keeps you cool, especially anywhere other than sitting in close proximity to it. 30 feet away, it won't.

DrewE

Vermont

Senior Member

Joined: 08/23/2014

View Profile


Offline
Posted: 06/01/21 04:14pm Link  |  Quote  |  Print  |  Notify Moderator

way2roll wrote:


Doesn't the dash AC compressor put drag on the engine thus decreasing MPG? I would think adding a second compressor would rob a good bit of power. The genset is far more efficient at producing power. I am not sure I believe the dash AC is more powerful but even if it were it's far less efficient at cooling a large space compared to the rooftop air.


The genset is actually not more efficient at producing power if you have to run the main engine anyway, at least not in the vast majority of cases. The main engine almost certainly has a better specific fuel consumption than the generator's engine (especially if the generator is an air-cooled unit). It might be true that running the generator is more fuel efficient in producing electricity than idling the main engine solely for that purpose, but if so that's primarily because the main engine has a lot more moving parts and thus requires more fuel to idle (and producing only a few horsepower for a generator is effectively idling for it). It definitely is often true that idling the main engine for a long period of time is undesirable for various other reasons.

An Onan QG3000 has a brake specific fuel consumption of somewhere in the vicinity of 0.9 lb/(hp*hr), based on its published specifications, which is twice (or more) that of modern automotive powerplants. To put it another way, the engine in my motorhome's generator is half as efficient at turning gasoline into usable mechanical energy as a modern car or truck engine.

Of course, when talking specifically about air conditioning, one has to also compare the efficiency of the engine driven AC compressor vs. the electrically-driven one in a roof air conditioner, the efficiency of the electrical generator and motor (for the roof air), any energy loss in the belt and clutch for an engine-driven unit, and many other such factors. And indeed, when driving down the road, in either case the fuel used for air conditioning is very much dwarfed by that used for simply moving an RV along the highway.





Reply to Topic  |  Subscribe  |  Print Topic  |  Post New Topic  | 
Page of 5  
Prev  |  Next

Open Roads Forum  >  Class A Motorhomes  >  All

 > Do you run house AC while on the road
Search:   Advanced Search

Search only in Class A Motorhomes


New posts No new posts
Closed, new posts Closed, no new posts
Moved, new posts Moved, no new posts

Adjust text size:




© 2021 CWI, Inc. © 2021 Good Sam Enterprises, LLC. All Rights Reserved.