Air conditioner while driving

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MikeyInNY

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May 13, 2010
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Location
Colonie, NY (Near Albany)
I have a travel trailer.  We are looking at a different camper for when we are retired, we don't need a TT as big as we have now.  But in thinking about a class c or class a, and I had a thought.  If the rooftop AC only operates when on generator/shore power, then while you are driving, does the engine AC put out enough to keep the whole RV cool?  I doubt class a or c drivers use the generator while driving just to run the AC, so does the inside of the RV get hot when driving?  I'm thinking driving through the desert during the day when it is really hot outside the inside must heat up.  I know they are well insulated, and many are white, but it still must get warm inside.

So does the engine AC keep the RV cool?
 
We have a Fleetwood Bounder 33U and yes, we run the generator while on the road to run the A/C. The cabin A/C will not keep up with the heat load during the warm months.
 
When we ordered our one and only MH we opted for no dash air.  Instead we,simply ran the generator to power the roof air to keep the whole coach cool.  Worked fine.
 
On a Class C, one can easily isolate the cab with a heavy curtain and the cab will stay cool with the engine A/C. The rest of the M/H may become uncomfortably warm, so napping while another person is driving may be a problem.

A Class A is harder to isolate the "Cab" area but it can be done.

I've also given this some thought because running the genset will lower you mpg by about 1G per hr. On the other hand, the engine A/C will raise the engine temp and increase wear & tear on the engine. When climbing grades, it may become necessary to turn off the engine A/C anyway. Lot's to consider.
 
MikeyInNY said:
I'm thinking driving through the desert during the day when it is really hot outside the inside must heat up.  I know they are well insulated, and many are white, but it still must get warm inside.
I do a lot of driving in the desert and usually I start out around 5 am and drive until 9 or 10 in the morning. That way I avoid the hottest part of the day. Yes the interior of the RV will get hot inside if it is hot outside. They are not well insulated, in fact they are poorly insulated.
 
If the rooftop AC only operates when on generator/shore power, then while you are driving, does the engine AC put out enough to keep the whole RV cool?  I doubt class a or c drivers use the generator while driving just to run the AC, so does the inside of the RV get hot when driving?

We travel six or so months per year during spring/summer. Generator and rooftop air runs almost all the time while we are moving. The dash air will not cool the motorhome interior. Comfort always trumps any other consideration.
 
I think your assumption is wrong - probably many or even most motorhome owners use their generator to power the house a/c system. Certainly most Class A owners do.
 
We always ran the generator to power the A/C while driving.  Our motorhome was a diesel, but the generator was fueled by propane.

Margi
 
As you can see, most elect to run their generator and roof top A/Cs while going dow the road.
But that scenario is not always necessary.
We drive a 95 33' Bounder and manage to keep the driver/passenger area cool with only the dash air. I make sure the dash A/C is working as designed and have plug all the air leaks in the driver/passenger area. I might note that the Denso dash A/Cs used by Fleetwood in the 90s, is far superior to any of the other brands of dash A/Cs in use today. Guess which A/Cs cost the manufacture the most to install.

Richard
 
the research i have read seems to indicate that using the engine ac will cause the engine to consume extra fuel, about the same amount of fuel that running the genny will use.
we use the genny and coach ac. our dash air would not come close to keeping the cabin cool.
 
DAN L said:
the research i have read seems to indicate that using the engine ac will cause the engine to consume extra fuel, about the same amount of fuel that running the genny will use.
I don't disagree with using the coach AC as apposed to the engine AC but the generator will use about 4x as much fuel as the added load to the coach. It's also 4x more effective......

The AC compressor take about 3HP from the main engine. That may equate to about 1/4G per hr on a heavy rig like a M/H. It can actually be more than that on the family car because it must be calculated on a % of the total consumed HP.
 
My flying fingers don't always land in the right spot.  ::) 

What I meant to add is that we also drove a 1995 Bounder, 36' diesel.  We could make do with the dash air when it was a little warm outside, but when we felt it was necessary (most of the time) we fired up the generator and ran the A/C. 

Our rationale:  we worked hard for our money, we're "old-ish", we want to be comfortable while traveling, and we didn't really care what that may or may not have done to our miles per gallon.  Your mileage, and your comfort, may vary.  :D

Margi
 
Tom and Margi said:
My flying fingers don't always land in the right spot.  ::) 

What I meant to add is that we also drove a 1995 Bounder, 36' diesel.  We could make do with the dash air when it was a little warm outside, but when we felt it was necessary (most of the time) we fired up the generator and ran the A/C. 

Our rationale:  we worked hard for our money, we're "old-ish", we want to be comfortable while traveling, and we didn't really care what that may or may not have done to our miles per gallon.  Your mileage, and your comfort, may vary.  :D

Margi

Amen- I have 12,500 watts of generator power and it is used running all 3 roof airs. if I had a 17,500- it would run all 4- sweating is for the kids in tents
 
Genny and roof AC only.  The only time I use the dash air is local trips at home like driving for service or fuel before a trip.  1 gallon an hour is a very small price for my comfort of AC, and already having the whole coach cooled when I arrive.
 
I run the generator when it is hot. I have been on the road in Texas at 109 and nice and cool on the inside. I am not sure the actual consumption with my 7500 quiet diesel generator but it seams to be about 1/2 gal per hour. I don't care how much it cost I plan to be comfortable when on the road. I have sweated cross country in a non ac car; I don't have to do that any more.
Bill
 
I don't disagree with using the coach AC as apposed to the engine AC but the generator will use about 4x as much fuel as the added load to the coach.

I'm curious about the data behind that statement. Generator fuel consumption depends on the load and most RV generators use somewhere around 0.5-0.6 gal/hr at 50% load. A 5500 watt generator will run two a/c's at the 50% load factor, so fuel consumption is quite reasonable. Even less if you only run the front a/c. which is usually adequate.



Amen- I have 12,500 watts of generator power and it is used running all 3 roof airs. if I had a 17,500- it would run all 4- sweating is for the kids in tents
Wow, Ernie, those must be some huge a/c units. A typical 15,000 btu rooftop a/c needs only about 1400 watts to run, so even  4 of them should be no more than about 6000 watts.
 
Gary RV Roamer said:
I'm curious about the data behind that statement. Generator fuel consumption depends on the load and most RV generators use somewhere around 0.5-0.6 gal/hr at 50% load. A 5500 watt generator will run two a/c's at the 50% load factor, so fuel consumption is quite reasonable. Even less if you only run the front a/c. which is usually adequate.
You're right...... I have no real world experience with mine yet. I was just going by what the book rates my 5K Onan @...... .9G per hr @ full load.

If it gets .5 at 50%, that would be roughly double what a (gas) M/H engine might consume for running the less effective engine A/C..... A diesel might be a "Push" in consumption........  ;)
 
My 5500 burns right at .5 gl per hr. running the fridge and 2 a/c units.

When on the road I run the dash air and the roof air. I got an RV to be comfy in. ;D
 
I doubt class a or c drivers use the generator while driving just to run the AC, so does the inside of the RV get hot when driving?  I'm thinking driving through the desert during the day when it is really hot outside the inside must heat up.  I know they are well insulated, and many are white, but it still must get warm inside.

Sorry, but your assumption is incorrect.  Most of us who live or spend a lot of time in the desert southwest use our generator to run the roof A/C while driving because the dash air is inadequate.  Also, on a long 15- or 20-mile uphill there often are signs to turn off your dash A/C because the engine might overheat.  By using the roof air instead, overheating becomes a nonissue.  And we don't really notice much change in fuel mileage while doing this.  Even if the genny use 0.5 gal per hour that's a small price to pay to be comfortable when it's over 100 degrees outside.  We usually only run the front roof air.  The bedroom get warm but some of the coolness drifts back there so it's not as miserable as if we were only using the dash air.

ArdraF
 

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