House vs. dash A/C on the road

[sharkbait]

Just took home Georgetown 341, my first motorhome after several 5th wheels. The dealer employee who checked me out on the unit told me that it was better economy to run the house A/C with the generator while on the road than to cool with the dash A/C. This seems odd. Any feedback?

[windrider]

I don't see how it is more economical. You have a run a second engine to make power for the house AC. Running 2 engines is not cheaper than running one, period. With that said, the dash AC will never cool the whole rig. If you ever need to get the whole thing cooler, then you will have to run the generator and the house AC. As long as you are comfortable, run the dash AC. Wait till you get to the campground with shore power, YOU ARE PAYING FOR, to run the house AC. My two cents, your mileage may vary.

[NWJeeper]

I don't see it as being more efficient but it may be necessary as Windrider pointed out to have to run both to cool such a large rig. Depending on several factors such as dark color full body paint and ambient air temperatures you may need to run the roof air. Remember that the truck AC was designed to cool a large car or truck, not a 34' motorhome. I have seen from others where they think this is a design flaw and poor practice that the engine AC can't cool a 35' rig which only shows their ignorance.

When things get really hot, sectioning off a part of the rig with a door or divider will help a great deal to reduce the amount of "conditioned space" you need to cool. You may also find that if it's hot enough and you have a dark rig that both ACs running may not even be enough.

[mr.ken]

I haven't tried myself yet since I'm new but on rv.net they claim the roof a/c is more fuel efficient. I'm taking a trip next week and I know the dash air can't cool the whole living area so I may need to use the roof air, but we shall see I guess

[ronhanson]

I prefer to take some load off the chassis engine and run the generator since it needs to be excercised anyway. At 50% load it's only consuming a little more than 1/2 gallon an hour, the fuel impact is not that great. You spent a lot of money on your rig to be comfortable camping, you should be comfortable driving also.

[cfsoistman]

Originally Posted by NWJeeper

I don't see it as being more efficient but it may be necessary as Windrider pointed out to have to run both to cool such a large rig. Depending on several factors such as dark color full body paint and ambient air temperatures you may need to run the roof air. Remember that the truck AC was designed to cool a large car or truck, not a 34' motorhome. I have seen from others where they think this is a design flaw and poor practice that the engine AC can't cool a 35' rig which only shows their ignorance.

When things get really hot, sectioning off a part of the rig with a door or divider will help a great deal to reduce the amount of "conditioned space" you need to cool. You may also find that if it's hot enough and you have a dark rig that both ACs running may not even be enough.

Could you imagine the velocity of the air if the dash AC was designed to cool the whole coach. The wife gets up to get a drink and can't walk back to the front of the coach. She looks like she walking in a hurricane. As for the driver the frost is forming on his forehead.
We use the dash AC when driving at night and early morning but mid-day on very sunny days the genny is running with the main AC Unit. The secret is to start running it before it's too hot that the thing struggles to cool the coach down. Cooler days we may use the dash AC and open a window and run the fantastic fan just to keep it comfortable.

[rockwood06]

Cfsoistman, I hope you get this. I sent you a PM and don't know if you got it but I have the Interactive Training DVD and Diagnostics Manual on R-22 and R-410A. I need to know how to get it to you.....Wade.

[cfsoistman]

Originally Posted by rockwood06

Cfsoistman, I hope you get this. I sent you a PM and don't know if you got it but I have the Interactive Training DVD and Diagnostics Manual on R-22 and R-410A. I need to know how to get it to you.....Wade.

Sent you a reply message. Thanks for the reminder.

[mr.ken]

I just got back from a trip and the dash ac was adequate for the front seats even in 100 degree heat but my 2 year old made it necessary to run tge generator about half the time. Maybe . 5 mpg difference at most

[cfsoistman]

We're leaving tomorrow to go home. 515 miles and we'll have the generator running with one AC on in the coach and the dash AC. It's going to be in the 90's so it should be ok with both running. Without running one of the AC units it's just uncomfortable for anyone behind the front seats.

Correction, We started out with one AC but ended up using both AC units to cool the coach. It was really a hot one on Saturday but we were reasonably comfortable on our way up the road.