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Cass Sumrall 05-27-2015 06:05 AM

Chassis AC or House AC on the road?
We just got a new 2015 Allegro 32SA & are trying to sort out the differences from our 2013 Itasca Sunstar 30T we traded for it.

With the Itasca we followed the advice of others & used house AC while on the road rather than chassis air because we were told it used less gas to run the generator than the extra gas to add the AC load to the engine. We also did not want to use propane on the road to power our fridge so generator was the only other option for that.

With the Tiffin we have a residential fridge that will operate off the inverter on the road so no concerns about propane. But the house AC would require the generator & it is a 7500kw as compared to the 4000kw for the Itasca.

Both coaches have the same V10 engine. What do others do?


Statgeek 05-27-2015 06:25 AM

Our last coach was a 35' gasser, so similar in size to what you are talking about. There's no way that dash AC could cool off that much square footage, and since we travel with kids, that wouldn't work.

I have read where some couples (ie no rear passengers) mount a heavy curtain behind the drivers and pass. Seats and run the dash AC. I think it's a false economy, personally, as the additional load on the V10 probably isn't worth it--may actually burn as much or more fuel than if you just used the generator.

I suspect you'll have to weigh the pros of not running your genie (can't think of many) versus the cons of trying to pull a heavy load and cool the passengers on one gas engine.

Also keep in mind that those genies are best maintained with periodic use. If you rarely or never boondocks, driving may be the best exercise your generator ever gets.

dezolen 05-27-2015 06:29 AM

We travel with chassis air on when on the road in our 36LA. Does a fine job for the 2 of us. I doubt it could be cheaper to run the genny. Never even considered it.

allegro1x 05-27-2015 09:18 AM

I use generator, when outside temp is 80 or above. We also have a 7,500 kw and it doesn't seem to use much gas. I had a Onan/Cummins rep service our generator at the Tiffin Rally in Orlando, FL in March and at his seminar he recommended running the generator a lot when you were on the road. By the way you might not know it, but the generator engine is a Subaru. Onan couldn't
meet EPA standards with their engine. Dave

garykk 05-27-2015 10:38 AM've spent big $$ on a new MH and you are worried about how much fuel you will burn running the genset:cool:

Brockx 05-27-2015 10:52 AM

It's just my Wife and I so we don't worry about the temp beyond the front seats. We have never ran the Generator for AC travel, the dash air has been more than adequate in both units we owned. We generally close the door rear of the kitchen and leave the roof fan in the kitchen on low speed.

My mind-set isn't about fuel use but excess wear and maintenance on the Gen-Set.

kalynzoo 05-27-2015 11:04 AM

We live in Southern California, so the first couple of days of travel in any direction involve mountains and desert conditions. The outside temp is often over 100 degrees (very often and very over). Therefore, we regularly run both the dash a/c and kick on the generator and run the house a/c at the same time. I believe I have always kept my RVs in good condition, and although the signs say to turn off the dash a/c when going over the Grapevine (I-5 leaving LA) I never do, and I have never had an overheating problem. My last coach was an gas 38ft Adventurer and I kept it 11 years.
Happy Trails.

gosman 06-13-2015 01:49 PM

I'm considering buying the 32SA and live in Texas. Nice to know that it can stay cool while driving down the road. However, we go to Colorado a lot. People are telling me to go diesel pusher for the mountain passes. Especially pulling a toad. What have been your experience in very tall mountain passes with your gas rigs?

Melmoses 06-13-2015 03:12 PM

Neither gas or diesel pusher will race up mountains. We had a Tiffin gasser and it did just fine. As far as running the gen set while driving, I do it in summer heat. On an says you need to exercise it at least 2 hours under load a month. We didn't do that on the gasser, called ourselves saving it by not running up the hours. Big mistake. We had all kinds of problems after a few years from lack of use even though we did maintenance as required for warranty. Fuel line clogged for one thing. Onan rep told us you need to use it. It is made to run, not sit. So now with diesel pusher we use it regularly and in 5 years not one issue. It has 876 hours on it. Our other one had maybe 100 after 5 years.

traveler of california 06-13-2015 03:39 PM

I had over 2000 hours on my generator of my previous MoHo. Made sure I ran it monthly, even during the winter. Everything I've read is it is better to run the thing than let it sit idle.

We always use the genny when it is hot outside as fuel consumption is minimal.

dabrooks 06-13-2015 04:52 PM

The other advantage to running the genny and house air is to keep that big box cooler in hot weather. Even if you are cool in the front seats on hot days it does not hurt to run the house air for the last couple of hours of your trip. With the darker colors of the newer model motor homes it takes them awhile to cool off if the sun is still up.

wa8yxm 06-14-2015 12:09 PM

I have heard many times that it is more efficient in terms of fuel economy to run the genny than use the dash air.


However.. If your aim is to cool he house.. the dash air will NOT do it. In fact it is doing good if it can cool the cockpit.. It is way too small.

Thus.. Use both.

kayak70 06-14-2015 02:30 PM

If it is hot outside we run the dash AC and the genset for coach AC as well. We have done that on our prior gassers and diesel. The best thing you can do for the generator is use it. It will last longer and provide better service with fewer problems and you will stay nice and comfortable which is why you have a motorhome:whistling::whistling::whistling:

One rig a long time ago, 06' WGO View, had a generator which used the coach LP as fuel - bummer. That was a bad move on my part, buying it. They had a LP fueled generator on a diesel Sprinter rig. Argh! We used it when necessary anyway, never had a problem with it but LP is harder to get than diesel.

PeaceOwl 06-14-2015 09:03 PM

Thnx for answering these questions, as we were wondering also but afraid to run both. Ok here's an added question...
If you were in 100* weather, going up a few grades, in the desert. End up in bumper to bumper traffic, worried (as the trucks were) about overheated brakes. Would you run both, one or no air conditioning? We went with the dash air, which was not efficient, 98* in back of van, just one miserable drive home, two hours in this situation.
What would you have done? Safe to run both in this case? Thnx mucho.

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