heating system question

<div class='quotetop'>QUOTE(camner @ Oct 9 2007, 10:28 PM) [snapback]523467[/snapback]</div>

Set it to AC/Auto with the temperature at 71 and forget it. The climate control system will not only maintain the temperature but remove any excess humidity that might fog the inside of the windows. Don't panic when it does not do exactly what you think it should. It will change the vents as needed.

 

I leave mine on Auto and it does just fine. Leave the A/C on too, as it is used for defrost, unless you are going to drive with open windows.

If you try to second guess the climate control system, it's going to drive you nuts. Don't worry too much about the actual temperature setting; if you want it warmer, bump it up a click or two. Just remember that if you chase the settings up and down you may induce oscillations, so give it a little time to settle after an adjustment.

Tom

 

Auto climate control systems aren't all-on or all-off like household climate control systems. They have a wide range of fan speeds, heat outputs, AC compressor capacity varies. They are also typically noisier than household systems, at least when they are working hard.

So if the actual and desired temperatures aren't very far apart, it will try to gently and smoothly adjust the temperature in the cabin. No hot spots, no blast of heat, no roar of noise. If the difference is larger, it will take more drastic action.

I'd suggest ignoring the actual number you see on the display. If you're cold, push the temperature up button. If you're hot, push the temperature down. After a year with mine, I've found that with that logic the actual numbers I command have generally always been between 70 and 75. I thought I would set and forget at first, and that's somewhat true, but depending on the weather, my state of dress, and my mood, I do fudge a degree or two on a day to day basis.

 

i like 72 on a warm day. 73 at night. if i'm cold 75 is good.

 

no matter what. only the defroster and lower vents put out heat. maybe it has to do with it's recirculation system. i'm not exactly sure why they chose that.

 

There are varying levels of "autoness" of the system. Some parts may be auto, while others may be fixed by the user.

The AC compressor can be set to "off" or "auto".
The fan speed can be set to a manual speed or "auto".
The vent directions can be set manually or can be "auto".
The temperature can be set to "max cold", "max hot", or "auto" (a specific temperature).

The system is designed to be left in full auto mode, with a desired temperature set. It will then adjust all the parameters as much as necessary to maintain that temperature and a comfortable humidity, as well as keep the windows clear.

There's no way of choosing a fixed "vent outlet temperature", which seems to be what you desire, except for "max cold" or "max hot". The vent outlet temperature is trying to push the cabin temperature towards the specified target temperature. So it's the only thing that can't be operated "manually".

Really, if you haven't given the climate control system a proper go in full Auto mode yet, do so. It'll be far easier than trying to force it to work like a non-climate-control system.

And as a previous poster said - if the temperature's not right, adjust the target. But I'd add that you should wait a while for it to settle. In my experience, I certainly wouldn't call 71F (=21.7C) "toasty". Mine's usually set at 21C, and that's comfortable.

 

<div class='quotetop'>QUOTE(seasalsa @ Oct 10 2007, 07:32 AM) [snapback]523525[/snapback]</div>

I must admit I am a little confused also, and what you and a few other folks have said makes sense, but.......(got my 07 Prius in Texas in May and have moved back to my home of Ohio so just now have had to deal with heat rather than ac on or off)

I have messed with the controls also, it is tedius to get the thing to put out heat without having to have the "auto ac" on.

But from what I am reading, really, as much as I would love to have the convenince of always just having to set a tempature from the steering wheel control, do I want the "auto ac" thing on even when it is 10 degrees outside? I guess I am wondering, is that a/c compressor on for no reason and also I feel a little silly driving around with "auto a/c" showing on my display when there is two feet of snow on the ground.

Am I thinking too much into this thing or is the car smart enough to realize that it is below freezing even though I have the "auto a/c on?

Sorry for the dumb question but I DID just go over my manual and it really does not talk about the heating system, just cooling......

Mike G
Dayton, OH

 

Move to Florida, we could use the revenue and at the same time solve the worlds biggest problem, "Climate control in the Prius"

 

<div class='quotetop'>QUOTE(tafkam @ Nov 23 2007, 03:24 AM) [snapback]543158[/snapback]</div>

Not sure if you're thinking too much, but there might be some terminology confusion. In your mind and talk, replace "A/C" with "climate control." That's really what it is, across all cabin temperature ranges. Set the temperature of the "Auto A/C" high in mid-winter, and it will put out plenty of heat.

When I use climate control (which actually is pretty infrequent) I use the Auto mode. It really is much more convenient than fiddling with the clumsy MFD controls.

 

If the car temperature is below the setting, the A/C (cooling) will not be engaged, unless you touch the "defog" button.

Like most Japanese cars, the centre vents will not blow heat. Only the ones on the outside of the dash will blow warm air (defrosting side windows along with the dedicated defrost vents to the outside and above them).

The fans will not come on until there is heat to blow. This takes a few minutes. Unless you have selected the "defog" again, in which case it will initially blow dried inside air (dried with the A/C system). Brrr. The ceramic heaters are around 400 W. Don't expect a lot of heat! Just think of how much current it would take to get nice heat from them at 12V (1000 W would require 72.5 Amps at 13.8 V). That's why they are not very effective. I can't even feel them here in the "Great White North".

I find it works best if I just get over the A/C light and select "Auto".

Messing with it just confuses it and you.

 

<div class='quotetop'>QUOTE(David Beale @ Nov 23 2007, 01:05 PM) [snapback]543323[/snapback]</div>

X2. The climate control won't blow cold air out the vents in your face. In addition it will keep the fan speed to low. You'll notice as you start driving (and watching the climate control in auto) that the climate control will slowly increase fan speed as heat is available. In addition you'll eventually get to the point where it will turn on some heat to your face by way of the face/floor option. I don't recall if it eventually goes to full face from the face/floor eventually as I usually turn the temperature down by that time (I'm in Arizona so this time of the year it's only 55F when I leave for work).

Mike

 

I've often thought a small AC fan heater in the prius to pre-warm it while the block heater pre-heats the engine would be a good idea in those northern climates. You would only need a couple hundred watts running 3 hours in the morning with the block heater just to knock the chill off.

 

<div class='quotetop'>QUOTE(tafkam @ Nov 23 2007, 12:24 AM) [snapback]543158[/snapback]</div>

Hello Mike

Sorry to be kicking the dead horse.. but..a/c does not always mean air conditioning in this car...or. air compressor

the car monitors the inside temp and humidity (it tries) and activates the commpressor when it's only needed.... so.. cooling, defrost, and high humidity times when the car is warm. also.. if the comnpressor does turnon..itcan still put out hot air.

so. leave it at a/c auto, unless you're extremely worried about mpg... if you're thatworried, block your grill (if possible) put a sheet of insulation aroundyour engine (again varies on climate), set the a/c to a comfortable temperature ( 72 daytime 73 at night for me ) then turn the system to low fan without a/c. you'll still have temp control but the fans willl never go past low. oh yeah..get a scanguage,and a plugin kit. that's about as "green" as you can get.

then again, does fan speed really mmake all that much of a difference? i wouldn't think so...

then again.. i ride on heavy 17 inch rims, leave my a/c on, get about 40mpg and don't care. auto A/C for Everyone! lol

 

Hey, thanks to everyone that responded to my question, it does make a little more sense now. I will try the "auto a/c" thing, even in the winter, fine with me if all I ever have to do is push the temp button up and down all year, that actually works out great.

One of the main reasons I got this car besides the milage was I really liked it as a car period, the controls, display, etc. I am a "gadget" lover and if I can control pretty much everything from the steering wheel, all the better, besides the fact that it has the speed right in my face in big green numbers so I don't have to keep glancing up and down and squint at a bitty speedometer due to my advanced age of 42.

Thanks again everyone and have a great holiday season.

Mike in Ohio

 

I have an '07 Prius. I have been trying to avoid using A/C if possible, in an attempt to improve my gas mileage. Living in a temperate climate, like Seattle, A/C is more about keeping the windows from fogging up. So I have alternated btw nothing and using the defrost. The cabin temps haven't been a problem. But after reading this thread, it raises a few questions. Comparing this usage vs Auto A/C all the time, is it's effect minimal? Also, I use the steering wheel controls a lot. I've found that to toggle the way I'm doing now, when I turn off the front defrost, it will automatically turn Auto A/C on. So I have to hit that button after I toggle the Defrost off. Does anyone know of an easier way to do this?

 

<div class='quotetop'>QUOTE(Aces @ Nov 25 2007, 11:06 PM) [snapback]544107[/snapback]</div>

You've described how I typically use my climate control in cool or humid weather -- just enough to clear the windshield. Whether its effect is "minimal" depends on how often you have to use it. I know the Pacific NW is a wee bit more humid than these parts, but I don't know how much more easily your windshield gets fogged. Around here, it's not often -- cold mornings on startup, and intermittently on humid days.

To turn it off, I simply hit the steering wheel AC button twice. First time turns off the defroster and turns on the Auto AC mode, and second time shuts down the whole system.

 

<div class='quotetop'>QUOTE(patsparks @ Nov 23 2007, 03:28 PM) [snapback]543378[/snapback]</div>

Well, this morning it is a nice cool -18C or 0F. A "couple hundred watts" heater wouldn't do much. That's a light bulb. Makes the interior brighter, but not much warmer. Even 1000W only brings the temp up to almost bareable (pun intended).

As I said, it's cool. We won't call it cold until it gets below -30C. It's darn cold at -40C/F, which is "bring in the brass monkey" weather.

I've been running the thought of insulating the car though my mind for the last few months. Just wondering how much help it would be, as you can't insulate all the glass, so added insulation in the roof and doors may not do much.