Running the roof A/C when traveling ...

[Hayseed]

We have a '75 26 foot Argosy with, what I believe is, the original roof air conditioner. I have a question ... what's the members take on running it when you're doing 60 MPH ??
The thing that concerns me is that the air flow (via the external fan) is in the back of the unit and out the top. The shape of the outside part of the unit (flat on the back) leads me to believe a vacuum will be created in the rear thus opposing the air flow the fan is trying to create. (I have the feeling none of this makes any sense.)
Any comments ??

[thenewkid64]

We just got back form a 2k+ trip from Tampa to Dallas and back. We ran the roof AC whenever we felt the dash air was not keeping up with the heat. Usally 10 AM to 3 or 4 PM. I ran 60-65+ on the way out with no trouble and the AC worked fine. I would not worry about it unless your AC is acting up while you drive. I think there is enough air flow in general at that speed that it would work without the fan.

[ALANSD]

I ran the roof air for most of a 2 week trip at 55-60mph and in 90 degree plus heat. It was comfortable inside most of the time, but when it got to 95+ outside, the driver's area was a bit warm from the engine heat leaking in. I had no dash air, as I need a "charge". The air coming out of the a/c unit was ice cold at all times, just was not qiute enough for the extreme heat and humidity. At 85-90 outside it was fine. I also have 2 small 12v dash area fans that help to move the air quite a bit. They are inexpensive additions.

[JW84345]

No problem running the roof air. The larger concern is the genset. Not an issue if well maintained.