Toyota Prius Forum banner

1 - 20 of 29 Posts

·
Registered
Joined
·
81 Posts
Discussion Starter #1
Although it is cold here now (in the 30s) I haven't really used the heat much - until today. Did not use auto - just set the temp at 68 and blower in midrange. All was fine for a while then all of a sudden I see Max cold show up on the climate screen and sure enuf very cold air was blowing in. WHY IS THIS?? Can I expect the a/c to come on blowing cold air every time I want heat? Is there a way to bypass this?

Another question: How can one tell what the temp. is in the car? or do you just set the desired temp. and never really know (except when the a/c comes on) when you have reached that temp.
 

·
Registered
Joined
·
81 Posts
Discussion Starter #2
:roll: I can't believe that over 155 people have looked at this post and not one of them has an answer!!
 

·
Registered
Joined
·
81 Posts
make that 164...
I wish I had an answer for you, but I don't. I hope to take delivery of my '04 sometime between the 5th and 10th of next month.
 

·
Registered
Joined
·
397 Posts
DAVID said:
make that 164...
I wish I had an answer for you, but I don't. I hope to take delivery of my '04 sometime between the 5th and 10th of next month.
This is the first time I've looked at the post and I'm responding. Maybe this will break the pattern. Anyway, my climate system does not pump max cold A/C into the cabin on its own. A few times, when I first had the car, it seemed like the system wanted to default to a setting like you are describing, but it doesn't do that anymore. I wish I could tell you what I'm doing differeently, but I can't remember. Now that I've found a setting that works for my climate conditions I leave it alone and everything seems to be fine.
Drive happy,
Moo :)
 

·
Registered
Joined
·
106 Posts
Hi Oldfox: Sorry you didn't get any replies at first, but I see now they're rolling in. I was going to mention something I've noticed, but I'm not so sure about it so I let it pass. What it was is many cars use acombinatiion of refrigeratiion and heat to defrost windshields. Perhaps in your case there was a momentary malfunction which hopefully won't recur. Keep your fingers crossed. Whatshisname.
 

·
Registered
Joined
·
1,434 Posts
I didn't respond b/c I didn't have the "Why" answer for you... and still don't. I wonder if, perhaps, you pressed the down arrow on the steering wheel by accident and turned the temp that low.

In any case, to avoid it in the future just use the auto setting...it works great, it will dehumidify when needed, it keeps the temp at a comfortable temp depending on your desires and only runs the fan when needed and thus is more fuel efficient.
--evan
 

·
Registered
Joined
·
81 Posts
Discussion Starter #7
:D Thanks to all - Guess I will try the auto mode for a while. Since none of you have had this problem I may end up taking it to the dealer for a diagnosis.
 

·
Registered
Joined
·
68 Posts
In auto mode any setting below 65F turns on max cool, no matter what the outside temp is. Since I like to have the car around 60-62 in winter when I am dressed warmly, and do not wish to get sleepy, when I took my 04 red9 in for it's first service I asked for a change. I had downloaded what can be done by service with a hand-held and there it was;
.AMBIENT TMP SFT (Ambient Temperature Shift) To control with the shifted ambient temperature against the display ambient temperature. NORMAL +3C/+2C /+1C/ NORMAL /-1C/-2C/ -3C
so now when the setting is 65F the car is actually around 61F.
Now I hope I don't go crazy in the summer. Peace, Ammiel
 

·
Registered
Joined
·
397 Posts
efusco said:
...perhaps, you pressed the down arrow on the steering wheel by accident
Oldfox,
As I was driving this weekend I was thinking about this thread and wondering if you had accidentally pressed the defrost button on the steering wheel. That might explain the scenario you are describing.
Drive happy,
Moo :)
 

·
Registered
Joined
·
81 Posts
Discussion Starter #10
Moo: No, I am sure I did not press the button on the steering wheel. I am anxious to try the heater/ac thing again but we have had quite a bit (For NC) of snow and ice and of course the Prius will stay comfy in the garage until the weather clears. My poor old 94 Explorer, faithfull and true with over 153,000 miles of trouble free driving is parked on the street and takes us around when the weather is like this.
 

·
Registered
Joined
·
4 Posts
Climate - A/C button

I notice that the A/C light turns on automatically when the "Auto" function is selected. Can someone tell me if this should be turned off when heat is desired rather than cool air? Or is it beneficial in some way to leave A/C on in the "Auto" setting no matter the temperature setting?

Jim, with a VIN, and hopefully picking up an AM on Saturday!
 

·
Registered
Joined
·
1,434 Posts
Re: Climate - A/C button

jreasus said:
I notice that the A/C light turns on automatically when the "Auto" function is selected. Can someone tell me if this should be turned off when heat is desired rather than cool air? Or is it beneficial in some way to leave A/C on in the "Auto" setting no matter the temperature setting?

Jim, with a VIN, and hopefully picking up an AM on Saturday!
A/C, in the Prius, does not mean "air cooling"--it 'conditions' the air to the temperture you set it at. If you have the temp set at 72 degrees and the outside temp is 50 degrees the A/C will warm the car up to 72 degrees. If the outside temp is 90 degress the A/C will coll the car to 72 degrees.

So, Yes, it is benefitial to leave the A/C on auto all the time unless you have some particular quirky reason for desiring manual control. The A/C control system in the Prius is very advance and very effective.
--evan
 

·
Premium Member
Joined
·
2,820 Posts
Re: Climate - A/C button

efusco said:
jreasus said:
I notice that the A/C light turns on automatically when the "Auto" function is selected. Can someone tell me if this should be turned off when heat is desired rather than cool air? Or is it beneficial in some way to leave A/C on in the "Auto" setting no matter the temperature setting?

Jim, with a VIN, and hopefully picking up an AM on Saturday!
A/C, in the Prius, does not mean "air cooling"--it 'conditions' the air to the temperture you set it at. If you have the temp set at 72 degrees and the outside temp is 50 degrees the A/C will warm the car up to 72 degrees. If the outside temp is 90 degress the A/C will coll the car to 72 degrees.

So, Yes, it is benefitial to leave the A/C on auto all the time unless you have some particular quirky reason for desiring manual control. The A/C control system in the Prius is very advance and very effective.
--evan
I much prefer the Auto fan selection
on the classic Prius - it'll regulate
the fan speed and the amount of heating
or cooling, to best meet the cabin
thermostat setting. You manually
set the position of where the heating
or cooling will blow at you.

In the 2004 Prius, the Auto setting
likes to decide where to blow air
at you, one moment just the feet,
the next at your face, later maybe
a mix of both...

Usually in the winter I'm nice and
bundled up (coat, hat, gloves, etc.),
but no matter what I wear my feet
are always cold, and if they're cold,
then I'm cold. In my 2001, I can
set the heat to only blow at my
feet, which keeps me nice and warm
(and doesn't annoy my sinuses like
air blowing at my face). In my
2004 Prius, I cannot use the Auto
function, as more often than not
it'll blow hot air at my face, and
leave my feet cold, making the
temp differences from the top to
bottom of my body even worse than
if I set it manually... Unfortunately,
I cannot get the auto-fan speed
setting without the auto-direction
setting, so I never can figure out
where I should set the fan speed
(spoiled by my 2001).
 

·
Registered
Joined
·
397 Posts
Re: Climate - A/C button

mrv said:
...In my
2004 Prius, I cannot use the Auto
function, as more often than not
it'll blow hot air at my face, and
leave my feet cold...
I have similar issues with the "Auto" setting on my '04. The best compromise I've found is to direct the air flow by using the defrost/feet combo button and turning the fan up a notch or two higher than I would if I were using defrost alone. This does a good job of keeping my windows clear and preventing popsicle toes. All in all I feel the Prius warms up quite quickly and maintains a comfortable cabin. I seem to recall reading somewhere that the ICE and electric motor work in tandem to supply heat, but have yet to find a link to anything difinitive.
Drive happy,
Moo :)
 

·
Registered
Joined
·
9 Posts
I just picked up my '04 Prius last night, so can't verify (yet), but on my Avalon I could pick the vents I wanted to use for heat outlet, but the rest of the system remained on automatic. So, as the cabin air warms in winter, the fan slows even if I manually select a vent other than what the automatic system would have selected. The only exception to this is if the front defroster vent is selected, in which case the fan goes on full until the car warms. I expect the assumption by the designer is that if you need front defrost you need it NOW. Which is almost always true in my case.

I was also able to turn the AC switch off if I desired. In the Avalon and in many other cars I've driven, having the AC on allowed the system to de-humidify the cabin air and thus result in less window fogging. This is particularly useful on cold, damp days with the car full of breathing humans.

Considering the heritage of the Prius, I expect the air handling system will be pretty much the same. It's cold this week, so I'll have plenty of chance to experiment with it. So far, it seems to behave as above.

FYI, I typically use the floor and dash vents together in winter, it keeps the wind effect on my face down while giving (I think) a more uniform cabin temperature. And my feet don't freeze.
 

·
Registered
Joined
·
9 Posts
OK, I can verify that what I said in my last post is true. 1) Because my experiments worked out and 2) That's exactly what the manual says, twice.

So, here's the story:

If you press the "Auto" button on the Climate Control unit, it totally controls everything. Air Conditioner (AC), heat, outlet vents, inlet vents, fan speed.

If you now press the AC switch, the air conditioner will turn off. This will save on gas if the AC is not needed. I guess it would save on gas if the AC was needed, but what's the point of having AC if you were planning to do that.

If you press the button for your outlet(s) of choice, only that outlet set will be used.

If you press the inlet button (recirculate or outside air) of your choice, only that inlet will be used.

You can do any or all of these and the FAN will still automatically increase or decrease speed depending on how far the set temperature is from the actual cabin temperature.

BUT, if you press a fan speed button, then the fan speed is determined by that button. Even then the system will attempt to control the temperature to the set point. It just won't be very successful.

Even better (this I found in the manual and verfied), if you press the windshield defrost button, most of the air will flow out the windshied defrost vents. If you press it again, the system returns to whatever mode it was in before you pressed it the first time.

Isn't that cool? Or hot, as the case may be.
 

·
Registered
Joined
·
81 Posts
Thank you for that clear explanation. I hope to receive my Prius in the next week or two, and have been wondering how the climate control works. (A fair amount of conflicting information out there.)
Thanks again,
 

·
Registered
Joined
·
81 Posts
Discussion Starter #18
TCBRT: :D :lol: That is the most clear and understandable explanation I have seen of how the climate control system works.
Thank You :D :!:

Now, if we ever get rid of this snow I will take the Prius out and put that knowledge to work.
 

·
Registered
Joined
·
397 Posts
oldfox said:
TCBRT: :D :lol: That is the most clear and understandable explanation I have seen of how the climate control system works.
However, unless you were mistakenly set in "Auto," or unknowingly pressed one of the front defrost buttons (steering wheel or screen), I still don't understand why your A/C came on unexpectedly.
Drive happy,
Moo :)
 
1 - 20 of 29 Posts
Top