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General air conditioning questions

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I

ichthos

Darth Vader
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I know they are more of a rarity for British cars, but in general, does air conditioning lower your mileage? If the air conditioner is not on, does it still have any effect on mileage or engine performance? Any help is greatly appreciated.
Kevin
 
Aside from the extra weight you are carrying around, there shouldn't be any measurable milage loss with the A/C off.

Running the A/C does of course affect your milage.
 
What I don't understand is, the AC is connected at all times by belt, correct? So why does it matter if it is on or not?
Kevin
 
The compressor is not always connected; there is a clutch between the compressor shaft and the pulley which is disengaged when the system is off.

Don't have it working on either Stag yet, but on my other cars, the effect on mileage isn't very much. Above 50 mph or so, the drag from the AC appears to be less than the drag from having the windows open.
 
A/C will drag on the engine. If the A/C is on then it will take about 5 +/- hp away from the engine depending on the compressor, and weather conditions of what it is trying to do as well as the speed the engine is running. Always driving the belt adds something but it is almost nothing. Just driving the belt and pulley takes something when rev the engine.

Also what TR3driver is saying is what I have been told with going over 50 and having the windows down.

I think it really comes down to how effecent is the the compressor.

This is what I have been told but I could be wrong.
 
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