Question about air conditioning power consumption

[voodoo22]

Hi:

Does the A/C use less gas if you run the A/C on recirculate, on a low fan speed, without turning the cold knob as cold as it can go?

Or, does turning on the A/C make you take a hit that's the same whether the cold knob is turned all the way or not?

Thanks for the info..... Bailout

[WRBlue]

The compressor has only two settings: on and off. Either the clutch is engaged and the insides of the compressor is turning with the belt and causing drag - and sucking up power, or the clutch isn't engaged and the engine is turning just a pulley. Fan settings don't matter for milage.

However, if your grounds are corroded (which they won't be for years), have a dying alternator (again, Toyo uses nice alts, should have 200k if it doesn't get wet), or have a dying battery, the current draw from the fans will tax the alt and cause more resistance for the pulley, thus wasting power and hurting milage.

Fan setting doesn't much matter either - the fan switch is a rediostat or however you say that, an adjustable resistor. Always have 12V going to it but by changing the resistance, you change the amperage draw. Which in turn increases the load on the alternator. But the alternator is sized more than big enough to not cause excessive drag at any fan setting.

[ern-diz]

Originally Posted by voodoo22

Hi:

Does the A/C use less gas if you run the A/C on recirculate, on a low fan speed, without turning the cold knob as cold as it can go?

Or, does turning on the A/C make you take a hit that's the same whether the cold knob is turned all the way or not?

Thanks for the info..... Bailout

been looking all over google for power consumption numbers when on recirculate vs. outside air and cool vs. ultra cold settings and haven't found anything yet...will keep looking tho, interesting question...

[kurokoma-kun]

Good info about the fan!

But if you crank up the cold setting, seems like the compressor will cycle on more often.

[black2yaris]

the A/C also comes on when you turn on the front defrosters Even if you have the heat all the way up ... this is soo the heated air blowing on the glass is dried by the A/C coil & not blowing moist air on a cold windshield ,which would fog right up ....
which in turn you have to remember....
that in the warmer months if you turn the defroster on at any time the A/C is ON ! as well drying the air blowing on the glass ..Even if you don't have the A/C button selected ,It is on anytime the defrosters are on ...

[black2yaris]

Originally Posted by kurokoma-kun

Good info about the fan!

But if you crank up the cold setting, seems like the compressor will cycle on more often.

'

No .......
the A/C pump is on or off no matter what .. the only regulators there are.. the fan speed control , the temp select knob . the coolant still moves anyway ,the controls are after the fact .......

[BailOut]

As has been said, the a/c is either on or off. No difference between varying levels of "on".

Recirculated vs. fresh air depends on a few factors but it basically comes down to this: It takes much more energy to both draw air in and send it out so the fan draws much more energy in recirculation mode, but if the outside air is so warm that you have to run the a/c system that much longer to cool everything off then it's worth recirculating.

If you absolutely have to use the a/c there are a few tricks to minimize the impact of it:

1) Use the recirculation setting to cool off the car, then the fresh setting to maintain the temp.

2) Only use the a/c on downhill slopes, turning it - but not the fan - off on level or uphill ground.

3) Don't run it longer than you have to. The car will stay cool for several minutes at a time so once it cools off turn the a/c - but not the fan - off for a while.

[kurokoma-kun]

Originally Posted by black2yaris

'No .......the A/C pump is on or off no matter what .. the only regulators there are.. the fan speed control , the temp select knob . the coolant still moves anyway ,the controls are after the fact .......

Well, sheeit... all through the summer heat wave I tried to keep cold setting as low as I could stand it... thanks for setting me straight!

[black2yaris]

Yaeh , if yer gonna have the A/C on then get the full effects as it costs the same in FE at any setting ...

[PetersRedYaris]

With the A/C on, some cars DO turn the compressor on and off as needed, the Yaris is NOT one of them. If the little green light is on or the defrost mode is on, the compressor is running all the time.

[ern-diz]

Originally Posted by black2yaris

Yaeh , if yer gonna have the A/C on then get the full effects as it costs the same in FE at any setting ...

this was always my feeling on it but, it would be nice to find some test data online somewhere, u know?...info on whether or not the components work harder when you're at a ultra cool setting on outside air -vs.- moderately cool setting on recirculate, and how it affects FE and power consumption...

[black2yaris]

Where is the Ultra-Cool button on a Yarii ?

[ern-diz]

Originally Posted by black2yaris

Where is the Ultra-Cool button on a Yarii ?

r u serious?...

[ern-diz]

Originally Posted by black2yaris

Where is the Ultra-Cool button on a Yarii ?

i just mean the difference between the mildly cold setting at the start of the blue bars -vs.- the coldest setting at the end...thats all...

[gonzo452001]

I keep mine on recirculate most of the time but not a night can make your windows fog up turn the a/c off about a mile from home

[caveatipse]

Here in southwest Louisiana, in the summer, when it is often 100 degrees with 100% humidity, you simply have tohave the A/C cranked on full fan, as cold as it gets, on recirc. There is simply no other way to cool the car. It sucks in terms of FE.