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Old 07-10-2014, 12:13 PM   #29
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Some comments and observations: YES, on many vehicles the A/C kicks in when you choose DEFROST even if you are wanting HEAT, why,, Well "Frost" or "Fog" or Dew (A watery mist) on the windshield is condensed water vapor, the A/C condenses the water out before the heater heats the air so it clears the windshield faster... HOWEVER.. You do not need the A/C. just an extra minute.

Many feel that using the Genny to run roof air is more effiecent than using Dash Air,, I happen to NOT be one of them.. But that said.. A lot depends on your coach.

Dash air does a poor job of cooling cockpit

Roof air, does not even try to cool cockpit Or at least that is how it seems on this coach.

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Old 07-10-2014, 02:14 PM   #30
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In our coach when the dash air was inop, driving in high temps with the sun shining would really cook us up front, to the point where we would spray ourselves with water to try and keep cool. The dash air working makes a big difference -- it can still be warm, but not baking hot. There's just too much glass to allow roof air alone work.


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Old 07-10-2014, 05:06 PM   #31
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Dash air will allow you to have some cold air blowing directly on you. Even if the cab isn't super cold that can make it tolerable to drive. That's enough reason for me.
Dick & Theresa
2007 HR Endeavor 36 PDQ
Lots of power to pull the toys I don't have time to use!!
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Old 07-10-2014, 06:15 PM   #32
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A thought for those that haven't considered it already. On those warm days, especially those where you find yourself driving into the sun all afternoon, you can run your cab AC on max or recirculate to pull air from somewhere near the floor on the INSIDE of the coach. This air is often pre-cooled, and in almost all cases much cooler than any air pulled from outside of the coach. At that point, the cab air has a leg up on getting that air cooled to the point where it's useful! Much easier for it to cool that interior air than it is to cool 100 degree outside air!

Pulling interior air also a big help when the roof AC's don't seem to be getting any/enough air on you. The roof AC's are cooling the interior air, and gravity will have that cooler air down on the floor without something to circulate it. The cab AC, when it's set to pull interior air (vs. outside air) will pull that cool air up off the floor, and blow it on your face!

Way more efficient running the cab AC on recirculate. Works the same way in cold temps. At that point it will be warming pre-warmed air from the interior vs. trying to warm cold outside air.
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Old 07-11-2014, 05:14 AM   #33
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One more important thing to check if your dash air isn't as cold as you think it should be. Check your vacuumn operated heater door. The door is moved by a small vacuum motor to open or close the air flow through the heater core. In most vehicles, the heater core always has hot water moving through it and, if the heater door doesn't close completely, you'll get hot air mixed with cold as it makes it's way to your vents.

I experienced this problem last year when a cracked vacuum line was keeping the heater door from closing. I thought the AC was at fault but it was working fine. The problem was the hot air getting mixed in with the cold air my AC was working so hard to make!
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Old 07-17-2014, 02:33 PM   #34
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I have been told by two different people, "better to run Roof A/C because engine runs cooler and you get better MPG" I am at a loss as what to do. Dash A/C not working, but I don't handle the heat very well.
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Old 07-17-2014, 02:46 PM   #35
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Required? Yes. Especially on a Class-A in Texas. Dash air counter-acts the heat that comes up through the floor. If you live in Maine, maybe not...

In regard to dash or overhead air:
Yes, you'll get better MPG by running overhead.
You're also running your generator, which has a limited lifespan (hours) and costs a lot to replace.
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Old 07-17-2014, 05:53 PM   #36
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I'm a pure newB, and this post is more logic than experience. Well, it's ALL that way for now, except for our last trip

Our dash air wasn't cooling us on our first trip, even after an A/C re-charge...and it became obvious that trying to cool a large area wasn't as easy as cooling a small one, so...

Eye hooks on left and right sides behind the seats, up top. Easy to deploy snaps and rope going from hook to hook. Old (nice looking, though) bedsheet sewn to fit the connecting line. Split bedsheet vertically to allow people to pass through on the way to the head. A half oz of fishing weights to keep things vertical and tight.

Nice cool driver's area. Genset stays OFF. Admiral is happy

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2003 American Eagle, 46K miles
...from Sept 2015
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