roof ac or dash air

Our experience has been that the dash air helps the driver and front passenger have nice cool air on their face but even with a vent open in the back to pull it back further...it did little to nothing @ temps of 90+ especially in high humidity area.

We found the dash air did not draw down engine power enough to be noticed. The genny will use approx. 1/2 gallon of fuel per hour.

Our dash air quit and repair guy says it will cost hundreds to fix it so...we just use the roof AC units.

The best thing to do is try it and see what works for your comfort level.

We believe in being comfortable. Our generator burns 3/4 gal / hr under a full load (7500W).

If people start scrimping or cannot afford the 1 gal/hr cost of diesel fuel to run there generator. Then down sizing may be a better option. Down-sizing would afford cost sayings.

By the way this past week North of Erie, Pa. required us to run our generator for 16 hours due to the weather. I do not mean to be derogatory or mean.

noe-place wrote:

JaxDad wrote:

noe-place wrote:
Dash air won't cool a 30 foot rv to the rear. If you don't believe me just ask DW who tells me she's turning on the roof AC because she's dripping sweat.

If you have the rearmost roof vent open the vacuum caused as you drive will pull out the hot air that convection pushes up, that then draws the cool air from the dash down the back to replace it.

It works very well on my 24' C, and fathers and friends large class A's as well.

Might work on 24' but not on 30' on up.

My buddy's A is 32' and my Dads is 38', it works just fine.

The problem with using the dash a/c to cool the m/h is not the cooling capacity of the unit, the system used in the Ford chassis is capable of (depending on RPM) producing 50,000 BTU's but at highway speed, about 30,000 BTU's. that is more than double the capacity of a typical rooftop unit.

The problem is the relatively feeble fan to circulate all that cold air around.

Dash air didn't come close to cooling the entire unit on my former 34' gasser, doesn't do it on my current 39' pusher. I use the generator and central air on both. My wife is very sensitive to heat, and for us, it's a matter of life or death (mine), so I don't worry about the negligible additional cost. Actually, I've never noticed a great difference, and it gives the generator a good workout.

GM

JaxDad wrote:

noe-place wrote:
Dash air won't cool a 30 foot rv to the rear. If you don't believe me just ask DW who tells me she's turning on the roof AC because she's dripping sweat.

If you have the rearmost roof vent open the vacuum caused as you drive will pull out the hot air that convection pushes up, that then draws the cool air from the dash down the back to replace it.

It works very well on my 24' C, and fathers and friends large class A's as well.

Might work on 24' but not on 30' on up.

JaxDad wrote:

noe-place wrote:
Dash air won't cool a 30 foot rv to the rear. If you don't believe me just ask DW who tells me she's turning on the roof AC because she's dripping sweat.

If you have the rearmost roof vent open the vacuum caused as you drive will pull out the hot air that convection pushes up, that then draws the cool air from the dash down the back to replace it.

It works very well on my 24' C, and fathers and friends large class A's as well.

Try that in a 40 footer in the South in the summer and tell me how cool you will be amidships. I rode with a friend one time whose generator quit working and he tried the vents open trick (he read about on the internet so it had to be true). The digital thermometer never got below 87 and that's not cool where I come from.

noe-place wrote:
Dash air won't cool a 30 foot rv to the rear. If you don't believe me just ask DW who tells me she's turning on the roof AC because she's dripping sweat.

If you have the rearmost roof vent open the vacuum caused as you drive will pull out the hot air that convection pushes up, that then draws the cool air from the dash down the back to replace it.

It works very well on my 24' C, and fathers and friends large class A's as well.

Hi,

If you have ducted air it may help to run it on the fan only setting to distribute the cooled air from the dash unit.

My roof air will cycle when I'm driving.

Dash air won't cool a 30 foot rv to the rear. If you don't believe me just ask DW who tells me she's turning on the roof AC because she's dripping sweat.

JaxDad wrote:
I think a few folks need a course in math. A standard F-series dash a/c is a little more than 3 times more capacity than a roof-top unit is.

That may be true, but getting that cold air circulated all over a 40 foot MH is a big problem. Doesn't much matter how cold the air gets unless you can send it all over. I assume the OP is talking about DUCTED air. By the way, I never was much good at math!!