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Aeneas

Air Conditioning And Fuel Economy

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I read somewhere that the air conditioning system on the Prius Gen 3 is powered by the hybrid (traction) Battery and not by the petrol engine. Is this so? I ask the question because on my old Rav 4 petrol consumption shot up - way beyond the normal 23 MPG!!! - when I switched on the air conditioning. Presumably if the conditioning on the Prius is Battery powered I can use it without having to worry about its impact on fuel economy?

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Yes and no!

The power from the HV Battery has to come from somewhere and usually its from the engine (unless you decend long hills all the time). The a/c on the Prius is much more efficient that normal cars as its electrically powered, but on full load can draw about 4kw of power from the HV Battery - which will run it down quite quickly and will require topping up.

So, if you have the a/c on full in town then you will find mpg's will drop - just not as badly as a normal car. Use the a/c normally with climate control and you will hardly notice any difference in mpg's. I noticed a small drop on really hot days but certainly not the 20% drop I would find on a diesel car. I do mainly town driving.

Also, the Prius is more efficient in warmer weather than in cold weather as the heater needs the heat from the coolant system as in a normal car and the engine will have to run a little more often in winter. This results in a drop of about 3-5 mpg's from the summer figures.

Don't be scared off by the above. You can actually run the a/c or heating for quite a while without the engine running from the HV Battery.

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Yes and no!

The power from the HV battery has to come from somewhere and usually its from the engine (unless you decend long hills all the time). The a/c on the Prius is much more efficient that normal cars as its electrically powered, but on full load can draw about 4kw of power from the HV battery - which will run it down quite quickly and will require topping up.

So, if you have the a/c on full in town then you will find mpg's will drop - just not as badly as a normal car. Use the a/c normally with climate control and you will hardly notice any difference in mpg's. I noticed a small drop on really hot days but certainly not the 20% drop I would find on a diesel car. I do mainly town driving.

Also, the Prius is more efficient in warmer weather than in cold weather as the heater needs the heat from the coolant system as in a normal car and the engine will have to run a little more often in winter. This results in a drop of about 3-5 mpg's from the summer figures.

Don't be scared off by the above. You can actually run the a/c or heating for quite a while without the engine running from the HV battery.

Thanks. "Use the a/c normally with climate control" - sorry I'm just a bit puzzled by this being new to modern cars. My last one was bought in 1996!!! Do you mean set the climate control to automatic, the temperature to low and then the a/c will come on and off to maintain the temperature that is set?

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Yes and no!

The power from the HV battery has to come from somewhere and usually its from the engine (unless you decend long hills all the time). The a/c on the Prius is much more efficient that normal cars as its electrically powered, but on full load can draw about 4kw of power from the HV battery - which will run it down quite quickly and will require topping up.

So, if you have the a/c on full in town then you will find mpg's will drop - just not as badly as a normal car. Use the a/c normally with climate control and you will hardly notice any difference in mpg's. I noticed a small drop on really hot days but certainly not the 20% drop I would find on a diesel car. I do mainly town driving.

Also, the Prius is more efficient in warmer weather than in cold weather as the heater needs the heat from the coolant system as in a normal car and the engine will have to run a little more often in winter. This results in a drop of about 3-5 mpg's from the summer figures.

Don't be scared off by the above. You can actually run the a/c or heating for quite a while without the engine running from the HV battery.

Thanks. "Use the a/c normally with climate control" - sorry I'm just a bit puzzled by this being new to modern cars. My last one was bought in 1996!!! Do you mean set the climate control to automatic, the temperature to low and then the a/c will come on and off to maintain the temperature that is set?

As you describe, but set the temperature to the one you want, e.g. 20 degrees. Setting it to low will just leave the aircon running continuously.

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Press AUTO, Set the temperature to a reasonable level (I stick on 22C) and if the AC button light is on the system will heat/cool the car to the set temperature.

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Although you may want to turn the temperature down to say 17C at the end of the day otherwise next morning when you start up, the Prius will run the petrol engine to warm the cabin up to 22C - goodbye mpgs.

Another tip is to use ECO mode to make the aircon use even less juice. It does however, also affect the accelerator response.

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