Re: XLE Climate Control

Humidity.

Let's hope the humidity sensor is not in any seat cushion.

In my Avalon, it starts in recirculate mode when the ATC thinks the interior is very hot compared to the desired temperature. Easy to see that is how it works by raising desired temperature and it returns to fresh air mode.

tending

switch

parameters

recirculate

notice

Thanks.

Then

FRESH

The last of this set of 3 posts really get into the fresh vs. recirc button on the Prius:

Depending on your temperature setting in regard to the outside temperature setting (and what the interior temperature is like to begin with), will depend on how much Recirculation vs. fresh air you get when you turn the AC on. You can get a combination of both at the same time. However, if you turn the Recirculation button on, you get 100% recirculation all the time, no matter what other temp/fan/AC controls you set.

Makes sense on a hot day with a hot car, low AC temp setting. Cool down fresh air from outside, blow towards the upper part of car (face vents, etc.). Recirculate the air from low (feet) ducts, as cool air drops while hot air rises. Less energy needed for AC usage. As the interior temp gets cooler, then you don't need to recirculate the lower air as much and can switch to just cooling down the needed fresh air.

That seems counter intuitive, Art. Let's say the outside temperature is

85ºF, the car has been sitting closed up in the sun with an interior temperature of 110ºF, and your ATC is set for 70ºF. Get in and start the engine. Seems to me the ATC would duct FRESH air (85ºF) into the passenger compartment, thru the cold evaporator coils, pushing the existing interior air (110ºF) out thru the rear deck vents rather than RECIRC the 110ºF air thru the cold evaporator.

--

Philip

"If a long train of abuses, prevarications, and artifices, all tending the same way, make the design visible to the people . tis not to be wondered that they should then rouse themselves."

- John Locke (1632-1704)

Art Begun wrote:

I've always thought of it such that you always want the coolest air going into the evaporator, so that the coolest air is coming out of the vents (cool in, cooler out?).

That is, in your above scenario, use fresh air until the cabin is down to 85 degrees, then recirculated from 85 to 70.

Good job.

If you upgrade to the latest Outlook Express, you don't need OE-QuoteFix's sigdashes fix.

So my Avalon is counter intuitive. What else is new. By the way, this is my 4th or 5th car with ATC. The Ford and Chrysler's do the same stupid thing when the car is super hot. I believe they do it because they are comparing interior temperature with desired temperature and never consider outside temperature in the fresh air/ recirculated air equation.

temperature is

tending

climate

Doug, if it needs to cool quickly, such as when you set it below 80, then recirc is the way its done. Just because its an auto system, you can manually over ride any feature you like. In fact, if you look a the panel, it will tell you which mode everything is in. Change anything you like.

Philip, if its moving, ie recir, its not stale. And if the AC is on, it becomes nice and dry. ;-D

The system doesnt measure humidity at all. It is a set parameter and will use fresh on defrost and recirc on any max cooling. Its easier to cool it down if you not using hot air form outside. as it reaches target value, it will swap off.

It does.

Art: In my body of Corolla information is a schematic of the '03 Corolla's A/C-heat system. It's the KISS system. No electronic crap controlling things the way some office puke thinks things should work, further compromised by a bean counter committee. ;^) I put DRLs in the same box of electronic junk .... money that should have been spent on making a rattle free interior.

--

Philip

"If a long train of abuses, prevarications, and artifices, all tending the same way, make the design visible to the people . tis not to be wondered that they should then rouse themselves."

- John Locke (1632-1704)

Art Begun wrote:

Ok, you and I are on the same page and .... were it not for musty, onion eating, coffee drinking, BREATHING, farting occupants within the vehicle, I would eventually switch from FRESH to RECIRC. See where I'm going? ;^) There is also (in my experience) a higher incidence of evaporator mold growth in cars normally operated in RECIRC mode.

About Outlook Express. I am running OE 6.0 and as you noticed, running QuoteFix with it. Has there come available a new OE release of late? The build I have is 6.00 2600. This version DOES screw up quote spacing.

--

Philip

"If a long train of abuses, prevarications, and artifices, all tending the same way, make the design visible to the people . tis not to be wondered that they should then rouse themselves."

- John Locke (1632-1704)

Ok now... which is it?

(A) All air is initially RECIRC'd until Set Temperature is reached, at which time a blending or alternating Fresh & Recirc occurs?

or...

(B) All air is initially FRESH until Set Temperature is reached, at which time a blending or alternating Fresh & Recirc occurs?

In either case, Fresh can be manually overridden with Recirc and visa versa?

--

Philip

"If a long train of abuses, prevarications, and artifices, all tending the same way, make the design visible to the people . tis not to be wondered that they should then rouse themselves."

- John Locke (1632-1704)

Rick... we're top posting this thread. Ahem! ;^)

Ok, so there's no humidity sensor in the plenum. Ok fine. Again, I find it counter intuitive to assert that is takes less time to cool existing passenger compartment air down to the Set Temperature when the passenger compartment air is hotter than the outside air, humidity not withstanding. Are you SURE this is what is happening? As another poster has suggested, the ATC should choose to initially intake air into the plenum from whichever source (Fresh or Recirc) is cooler ... which apparently what is happening only when the passenger compartment nears Set Temperature, at which time a blending of both occurs.

In a pig's eye! If outside air is not continually entering the intake plenum, then you must be fan forcing the recirculation of TRAPPED passenger compartment air ... soon to be more accurately described as "stale air." Yeah, just what I need to keep me awake at speeds under

60 mph ... rebreathing the various odors associated with human occupancy. Argh.

--

Philip

"If a long train of abuses, prevarications, and artifices, all tending the same way, make the design visible to the people . tis not to be wondered that they should then rouse themselves."

- John Locke (1632-1704)

For the climate control for the Prius, it's both.

air is pulled in through the main vent, for the face area.Some recirc initially through a smaller vent, low in the cabin (recircthe cool air that settles down), less recirc as the cabin gets cooler/closerto the set temp.

Since I don't have a nose where my feet are (good thing, too!), I don't worry about the recirc near my feet.

(A) The thread is not about Prius. Prius .... from the moment you tell the computer to start the engine ... is a law unto itself.

(B) I don't care what Prius does once cabin temperature is achieved. The recent discussion is about the sequence of events from a hot car parked in the sun TO the target cabin temperature when the ATC is set and allowed to run its program without interference. While the link you provided is instructive, I would prefer to see the plenum schematics and read Toyota's technical.