Auto air question

<div class='quotetop'>QUOTE(bubba_steel @ Jul 23 2007, 05:23 PM) [snapback]483845[/snapback]</div>

No, you do not have to turn it off. The A/C compressor is powered by an electric motor unlike your previous cars. That also means that you don't have to worry about overheating when in stop and go traffic.

I leave mine on Auto with the temp set at 74. The Prius climate control system is very efficient.

 

<div class='quotetop'>QUOTE(bubba_steel @ Jul 23 2007, 08:23 PM) [snapback]483845[/snapback]</div>

No.

The air conditioning is run off the High Voltage System so it puts no load on the engine directly until the engine is running and up to speed. Also keep in mind that the engine automatically starts and stops (with the AC on) while at stop lights and low speeds, so the Prius is fully engineered to operate like this.

Edit-seasalsa posted while I was typing. Sorry for the repetition.

 

what sea said - set it to automatic, on 74 (or higher) , and forget about it.

 

<div class='quotetop'>QUOTE(bubba_steel @ Jul 23 2007, 09:53 PM) [snapback]483881[/snapback]</div>

Nothing magic about 74. Use a temperature that is comfortable for you. I usually set mine lower than 74, otherwise I'm using heat most of the time. It all depends on where you live, what temperature you like, and how much of a mileage nut you are.

Tom

 

Hey, bubba_steel! Welcome to PriusChat! Sorry for all these rude boys not saying welcome. Congratulations on your new car.

One thing to keep in mind, the HV battery is comfortable at the same temps you are. So if you're sweating with the AC off trying to get better MPG, you could in fact get lower MPG if the HV battery gets hot and inefficient. The air conditioning system (which can automatically cool, heat, and dehumidify) is great at keeping you and the big battery happy.

Enjoy driving!

 

<div class='quotetop'>QUOTE(seasalsa @ Jul 23 2007, 08:45 PM) [snapback]483854[/snapback]</div>

Congrats on the new car. Get an Engine bolck heater for the winter to install now while it is warm. It will really help with your first 5 min bar for consumption. I will install it if you live near the Augusta, GA area.
D Rock

 

<div class='quotetop'>QUOTE(Bill Merchant @ Jul 23 2007, 11:03 PM) [snapback]483959[/snapback]</div>

if the ac is powered off electric does that mean while cruising down the freeway it doesn't affect my mpg at all like in a normal car???

 

<div class='quotetop'>QUOTE(GatorJoe @ Jul 27 2007, 02:50 PM) [snapback]486302[/snapback]</div>

Nah, eventually that electricity will need to be put back into the battery and so overall your MPG will still suffer a bit from using the A/C.

What it does mean is that when the car is stopped for a short period of time (stop sign, stop light, etc) the Prius can shut the engine off so it isn't burning and wasting fuel. The Prius A/C compressor and environment controll system is very efficient and very well designed. So, while you'll still affect your MPG a bit by running the A/C you won't affect it as much as you would in a non-hybrid car with a belt driven compressor connected to the gas-powered motor.

Also, the battery works much more efficiently when it is not too hot or too cold. On a hot day, I doubt it is enough of an improvement to completely compensate for the energy used to run the A/C, but every little bit helps.

My estimates are that the A/C on a 90 degree F day in full sun at noon uses less than 0.1 gal. of fuel per half hour.

If you are driving 65 MPH for one hour in full sun at noon when it is 90F outside with the A/C on, and if you typically get 46 MPG without the A/C (1.41 gallons). . . .

A rough estimate would be 1.56 gallons used with the A/C or 41.7 MPG.

YMMV

 

Related questions:

-how to you put the AC into VENT mode?
-Why does it have this thing for keeping recirc on all the time? Somehow I don't think recirculating the 140 degree inside air is a good idea when its 110 outside.
-Why does it always select top-only vents?

 

<div class='quotetop'>QUOTE(Phoenix-D @ Jul 27 2007, 03:19 PM) [snapback]486379[/snapback]</div>

Evidently you did not leave it on long enough to go through the cycle. Tony Schaeffer did a good job explaining the AC operation.
TonyPSchaefer
01/30/07
Here's why it blasts at you when you turn it on:
Human comfort is a blend of temperature and air flow. In addition, the faster the Prius can exchange the hot air for the cold air (or vice versa) the sooner it will reach your specified setpoint. The variable speed of the fan is common in commercial building applications and here's my “lay-man’s terms†explanation of how it works:
Think of the fan speed as a function of the difference between current temp and setpoint. The fan will always run in order to maintain airflow and avoid stagnation, so "1" is the lowest possible speed unless you intentionally shut it off. So even if the CurrentTemp is the same as the Setpoint, Auto A/C will always run the fan at “1â€.

If you wait for equilibrium and then change the Setpoint (say, from 60 to 65), there will be an increased variance between CurrentTemp and Setpoint. To compensate for this, the Prius will add heat to the air and increase the fan speed. If you continue to increase the Setpoint, the fan will likewise increase in order to exchange more air faster until the difference between Setpoint and CurrentTemp is so great that the fan is operating at maximum speed attempting to keep up.

Therefore, DLP, the next time you hit the Auto A/C and the fan blasts, leave it alone. Depending on the situation, there might be a great difference between CurrentTemp and Setpoint. It will continue to blast for as long as needed and then you will notice it slowing down. As the CurrentTemp approaches the Setpoint, you will also notice that the air being blown is not as hot/cool as it was before. Additionally, if you keep the screen on the “Climate†screen, you will see that the vents selected for blowing air will automatically change accordingly.

I’ll tell you what, in my opinion, the Prius A/C/ system truly is one of the coolest features of the car. I mean, I sell this car every time I tell people about it. I can do a whole routine and have them mesmerized with its sophistication and engineering without even mentioning the part about it being a hybrid.