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Old 08-03-2012, 09:33 AM   #4 (permalink)
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The SCUD - '15 Fiat Scudo L2
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Originally Posted by Synchronicity View Post
Just wondering, if I'm going down a long hill and not pressing the accelerator pedal, it won't hurt mileage to turn the A/C on will it?
When you're having to use engine braking while going downhill in gear, the AC will be driven by gravity, and won't use any juice.

I'm wondering: does the air conditioning run from the alternator or it's own drive belt...?
They usually have their own belt & clutch to engage / disengage the AC compressor.
Though I seem to recall some cars having electric AC , and with stop/start systems the AC keeps running despite that the engine is off ... so they either recycle the air, use an electric compressor, or would have to restart the engine to power the AC.

I've been switching on the aircon on the downhill sections and turning it off for long uphills. I'm guessing this will improve my fuel economy?
It should - unless the engine load is so high during the climb that the AC would be disengaged anyway, in which case it wouldn't matter.
Strayed to the Dark Diesel Side

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