2nd Gen Non-Engine/Transmission AC use

[dfriend]

Does the AC use more power than the areodynamic drag of leaving the windows down when driving at highway speeds?

 

[Shovelhead]

I believe that the Ram is more fuel efficient with the windows up and the A/C on.

 

[MJawsman]

I read something somewhere that said ANY current model car is more fuel efficient with the windows UP and the air ON at speeds above 45 mph. Sorry I have no reference to post with this info.

 

[Dennis Garrett]

On my EGT gauge, I see about 25 deg hotter with the AC & Cruise on. I guess you might be able to figure a percentage greater & calculate that out to mpg.

 

[Lurch]

But the EGT raise is due more to the heat from the AC into the intercooler air flow than load related.



Lurch

 

[Shovelhead]

Wouldn't the boost gauge be a better indicator?

It should be reading higher under a greater load at a given speed , or am I way off base?

 

[McDowra]

Don't know about truck but I am more efficient with windows up and AC on.



Tim

 

[Charley]

I'm with Tim.



Charley

 

[Skydiver]

Man it's humid down here!

Charley I am with Tim also.

Nice to see another Alabama TDR member.

Tim

 

[HC]

Best is, AC off windows up.

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I believe the "windows up, AC on is more efficient" statement that is often heard applies to smaller cars that are typically more aerodynamic than our trucks. I seriously doubt it would be true for us. I've watched the trip computer pretty closely, and rarely can I make it change the instantaneous MPG by turning AC on or off. Based on that alone, the impact of using AC must be something less than 1 mpg. If my potential savings (windows up) is less than 1 mpg, and I'm losing some of that by rolling down the windows, then any net savings must be very small (<0. 5 mpg).



I run without AC early in the morning, or at other times when I can with reasonable comfort, but if it gets hot enough that I need the window full open, the AC is coming on.

 

[Missouri Mule]

A/C off, vent on, windows up = best mileage and resonable comfort.

Second best A/C on widows up.



To much air coming in, back window would act as parachute even if cc/qc back windows were open.

 

[athompson]

When it's 115 outside (but it's a dry heat), I don't care which is more efficient. I'd rather have it cool inside the truck. It costs less to run the A/C in the truck than in the house ($270 power bill last month).