A/c Cooling Vs Mpg -- Update.

[wwest]

Strange.....

I expected that my suggested use of the A/C posted earlier would result in better highway MPG which it does, ~22MPG with factory A/C vs ~24 with new method.

But the improvement in city MPG seems to be on the order of 30%.....!!

After thinking about it a bit I think I understand why.

The average speed in the city is quite low so it takes significantly more time to get from point "A" to point "B" relative to hwy. Higher percentage of time the A/C is being used vs vehicle moving forward.

Neat surprise.

[monarch]

Using the AC has a minimal negative effect on power and gas mileage in my experience with a wide variety of Toyotas, both new and vintage. The AC compressor is just a little 5-10 cubic inch motor so it shouldn't have much of an effect just like driving around with an extra 200 lb passenger shouldn't have much of an effect.

[wwest]

I suppose that's why most manufacturers open the compressor clutch circuit at WOT even on 300HP engines.

And during idle/stopped times when the A/C clutch kicks in it opens the throttle further to maintain the engine idle rate and prevent it from stalling.

[jerryray]

Strange.....

I expected that my suggested use of the A/C posted earlier would result in better highway MPG which it does, ~22MPG with factory A/C vs ~24 with new method.

But the improvement in city MPG seems to be on the order of 30%.....!!

After thinking about it a bit I think I understand why.

The average speed in the city is quite low so it takes significantly more time to get from point "A" to point "B" relative to hwy. Higher percentage of time the A/C is being used vs vehicle moving forward.

Neat surprise.

Where is the "suggested use of the air conditioner"

Thanks

[wwest]

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