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It took me a year to warm up the the concept of Auto/AC. I was continually flipping to the climate screen to control the fan. Now I am comletely sold on the thing. Hit one button on the steering wheel and then adjust the temp up or down as desired. It works for both heating and cooling, and the fan will blow hard at first and slow down as the desired temperature is reached. If you aren't using it, give it a try!
 

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I'm not sold. The fan speed the auto setting selects is always too low for me. Air movement can be very cooling in summer, and the auto setting darn near shuts off the fan when the set temp is reached. This also bakes the rear passengers. I almost never use the auto setting because of this. I set the fan to about the middle setting and then temp manually. I'd use auto if I could bias the fan speed up in software.
 

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I use the Auto A/C continuously and have for over a year. In March I drove from PA to FL and left the temperature set at 73. It was nice and comfortable for the whole trip. I never had a vehicle with Auto A/C before the Prius. Now I wouldn't buy one without it.
 

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Hep said:
It took me a year to warm up the the concept of Auto/AC. I was continually flipping to the climate screen to control the fan. Now I am comletely sold on the thing.
I was totally the same way. Its a perfect description too! I always flipped back and forth chaning fan speed. Now I just use the A/C Auto button and Im set! :)
 

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Before we got our Prius, my wife's car did not have temperature control while mine did. It's funny how quickly I would forget that her's had to be manually adjusted. Everytime I drove it I would be thinking things like "Why is it getting so #$%&$ hot in here?!" and "Why is that fan making so much noise all the time?!"

Now we both have temperature control and life is goooood.
 

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OK, I tried to give you guys the benefit of the doubt. I decided that today at lunch I'd try the Auto AC to see if I could put up with it.

The answer: No freakin' way.

The reason: I can't handle the fan running at full speed. When running the AC manually, I NEVER turn it higher than 2 or 3.

It was 88 degrees outside. The inside temp is set to 75. I turn on the Auto AC and immediately the fan turns onto the highest possible setting. We cannot converse or hear the stereo.

Being the genius I am, I think "Maybe if I raise the setpoint for the temp, the fan will slow down". I raise it from 75 to 80 and the fan slows down a couple notches (still well over halfway). I raise the temp some more hoping to see the fan go down to a comfortable setting of 2 or 3. No dice.

I keep raising it until, at one point, the heater kicks in and the fan goes back to full speed. Geez.

I this the same behaviour everyone else sees? I realize that after a while the fan will reduce it's speed as the car cools, but why does it have to come on at full speed? I'm just going from 88 to 75 degrees. It's not like I've set it to Max Cold.


DGStan
 

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VERY different behavior than my car on Auto.

Max fan only when I have it set at about 70 or below. At 78 (comfortable for me if it's aimed at me), the fan speed drops down to lowest or second lowest. No more air for the back seat, and pretty soon I'm getting complaints. So I set it cooler to get the fan speed up, and the ICE runs more and I freeze.

Set to midway on fan, and to 76-78 on temp, I can keep everyone cool and can hear the stereo fine. This is while it is 85-100 outside.

So I have the opposite problem-- too LITTLE fan on Auto. Weird!
 

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I think the auto function can be adjusted by a scantool. I can't remember what adjustments can be made.

The reason it blows at full speed is cause it's programmed to cool the interior down as fast as possible. You can help by driving with the windows down for a minute or two to blow the hot air out. It'll help the fan and cool the interior down much faster.

In manual mode, my fan is usually at LO or at one notch above. In Auto, I'll let it decide. It works better that way.
 

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Fan speed control is not one of the HVAC customizable options except for defrost.
Temp shift for cabin and outdoor temp (in case the display is wrong or you want to fool yourself)
Air inlet mode to set to recirc for quick cooldown
Compressor mode where Auto will enable or disable the AC automatically
AC override with front defrost
Foot/Def mode for quick cooldown
Blower level when in defrost
Foot air leak
 

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KTPhil said:
I'm not sold. The fan speed the auto setting selects is always too low for me. The auto setting darn near shuts off the fan when the set temp is reached.

My insight has the exact same problem. When the Auto reaches 70 degrees, it shuts off the fan. Then I bake in the sun.

So, I over-ride the fan setting and run it at maximum.

troy
 

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Played with it some more last night and this morning. I'llm odify my complaint a bit.

When it's hot out, the fan speed stays high enough after reaching the set temp. However, with it cold out, I like to run the system without the compressor. This morning it was 72 outside, and I had the car set for Auto, 68, with A/C turned off. This way, I should be getting fresh cool outside air (cooler than inside anyway). But under these benign conditions the fan is set to a very low speed,a nd the car heats up from solar radiation. I have to manually set the fan speed to the middle setting to not get too stuffy. I guess having the A/C off screws up the Auto fan speed calculation.

No biggie, since a couple of buttom pushes and I'm fine. But it does mean I don't use Auto very often.
 

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First off, the AC is also used to dehumidify, and that is part of the amplifier's calculations.
Second, the system also takes into account solar radiation. So even if it is 72 outside, it will pretend it is higher to make you feel cooler.
But you turned off the AC, so you disabled both those features.
 

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DanMan32 said:
First off, the AC is also used to dehumidify, and that is part of the amplifier's calculations.
Second, the system also takes into account solar radiation. So even if it is 72 outside, it will pretend it is higher to make you feel cooler.
But you turned off the AC, so you disabled both those features.
Yup, cool isn't everything. Drying out the air helps make you feel cooler, too.
 

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It's already dry in SoCal--no need to dehumidify, so it wouldn't be running anyway.

I just want fresh outside air with a reasonable fan speed. Can't get it on Auto.
 

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Yes you can. Hit Auto, then Recirc on the steering wheel so that the recirc indicator is not lit on the dash. Then go to the climate screen and press A/C soft button.
Set the temperature desired.
You are now in Auto, with fresh air, but no AC.


But then, you may not agree with the system's chosen fan speed.
 

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Exactly, my complaint is with the fan speed (or lack of it). On cool morning when I want fresh air, the Auto setting fails to drive the fan fast enough once you turn off the compressor.

OAT is in the 60s or low 70s, so I don't need chilling , nd the air is already very dry. No need to run the compressor--it just wears it out and drops mpg. I can't imagine what rebuilding this electric A/C will cost eventually!

But without the fan running, I get very little air flow, so the back seat passengers feel it getting stuffy from the lack of airflow.

Therefore I must hit the fan higher, thus taking it off Auto.

It's no biggie, just a few buttons, but it's strange behavior from the system.
 

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I don't understand why you keep saying "without the fan running". It will run whether the compressor is running or not.

Also, just because the AC compressor is "on" it is simply enabled. It will turn off automatically if not needed. I have observed this even on a warm day.
I had my car in the garage (exhaust pointing out) and since the cabin was warm, the AC went wild. Soon though, the cabin cooled and the compressor speed slowly dropped to its lowest point. Then, the cooling fan turned off, indicating the compressor was off. Occasionally the compressor and fan kicked in, shortly after the ICE kicked in (SOC was low by that point). This is observing by the engine compartment.

So, having the AC "on" doesn't mean it is actually running.
 

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You two sort of have me confused now. Living in a sometimes mild climate in the summer (as today when temps will be in low 70's) I select climate on the MFD, then "auto AC," then disarm the "AC" and select "airflow thru the car" and then have any fan speed I desire for outside airflow. Is it the few seconds you are speaking about to accomplish this?
This is the way I have been setting up the AC system in just about every car I've had since the advent of AC. Albeit, with a different set of "buttons, or knobs."
 
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