I have a Toyota Highlander with an automatic climate control system that totally baffles me. The issue concerns the option to either bring in fresh air or recirculate the cabin air.
Consider what happens if I keep the system in "auto" mode. When I get in the car on a hot summer day, it's blisteringly hot inside the cabin. When I turn the car on, the air recirculation mode goes on. So, instead of bringing in the relatively cool outside air, the car recirculates the much hotter cabin air and tries to cool that down.
Later, when the cabin air finally cools to a comfortable temperature, the system goes from recirculation mode to fresh air mode. So now, instead of recirculating the cool cabin air, it tries to cool down the much hotter outside air.
When I get in the car on a cold day, the cabin air, while cold, is still much warmer than the air outside. When it's cold, the system always picks the fresh air mode. So, instead of trying to heat up the cabin air, it tries to heat up the much colder outside air. Of course, I can almost always override the programmed choice by manually hitting the cabin air recirculation mode button.
I say "almost always," because if it is very cold outside -- less than 32F -- the cabin air recirculation button is disabled. That means it takes much longer to heat up the really frigid fresh air. Apparently, the system is worried that with cabin air recirculation, I might mist up the window and not be smart enough to turn it off or turn on the defroster. I can think of no circumstance where the system's choice is any other than the opposite of what would make sense.
This entry was submitted by Michael Holtz and edited by Rob Spiegel.
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The Highlander is not that old a car model so this one really seems baffling. What could possibly have driven the Toyota engineering team to design the automated climate controls in that manner? If there a glitch with your particular car or is this just a greater design flaw in the model or perhaps with the Toyota car platform in general?
Rob kindly published my views on my monkey designed Toyota a while back, and while I listed lots of issues then, I completely forgot about my climate control issues which were the same as these. It seems like they don't have someone on their design team that understands thermal management. They also didn't understand lighting, as the vehicle had 2 map lights but no light baffle between them, such that the pasenger's map light affected the driver. It also had one of those lovely sunglass holders in the roof lining that was too small for a pair of adult sunglasses.
This looks like yet another pointless automation of a car system that should always be user-controlled or at least user-controllable. My car, thankfully, is old enough that I can decide which mode I want to be in, combined with how much airflow via fan control and whether that air is heated or cooled.
Good point, Ann. I agree the automated systems may not deliver much value. I don't find it that difficult to manage the cooling and heating system in my older vehicle. There are subtleties to the system that can only be managed manually.
I agree, Rob. It's like the analog volume control knob on the stereo--sound control is an analog thing so that works better to the tuned ear than a series of preprogrammed steps. In this case, it's not linear but interactions that, apparently, require subtleties. I don't get why these functions were automated in the first place.
I'm with you on the volume control, Ann. Manual control offers more subtlety. Same thing with radio controls. I found the old dial worked better than most of the digital station finders.
I had an Oldsmobile Achieva that had a volume control knob with ratchets on it that required pre-determined intervals ofvolume control. The best I could do was get the volume to a point that it was either a little bit too soft or a little too loud. This was just one reason that I did not care for that car.
Interesting, Tim. A small item like that can help determine whether or not you like a particular car. This is a good example of a change to digital just for the sake of digital. You actually lose a degree of control with the upgrade to digital.
Reading your comment reminds of a similar useless feature in a previous vehicle I had where the volume would "adjust" to louder or softer as the velocity of the car increased or decreased. The thought of course was this would be a convenience to the driver turning the volume up as the car went faster and the volume down when the car slowed. In the end the best part about this feature was the fact that I could shut it off.
jmiller, that takes the cake. Who could have thought anyone wants volume to change with changes in car speed?! No relationship at all. Do you remember what make and model that was?
I hate it when I get asked a toucgh question. I think it was a chevy impala that I had. The feature was called auto volume. Kind of a neat idea. But it didn't really work the way they said it would. It "sounded" like a good idea, though.
jmiller, thanks. I remember the Chevy Impala. I still don't get why anyone would think that changing volume along with changes in car speed--regardless of which direction--would be a good thing.
I'll admit the concept is sound. Sorry fo the pun. When the car is going faster and the wind noise is more turn up the volume. And when the car is going slower and the wind noise is less turn the sound down. However, it's difficult to fine tune a system like this and in my opinion I was given a feature that really didn't help the consumer. And I hate that. Extra stuff that you pay for that looks good on a marketing board but costs extra and doesn't provide extra value.
Oh, d'oh! I rarely drive with the windows open while listening to the radio. Now I get why that feature might make sense. But the whole concept sounds like it would be pretty complicated in implementation.
I have the same situation where I have to turn up the sound when I'm going faster. Even though the windows are closed the wind sound still raise the ambient sound in the car considerably. Maybe it's because I have an older car. Maybe it's because it's a minvan and hits the wind like a wall.
Listening to classical music, I find myself turning up the volume on the soft passages and turning it down on the louder passages. I always thought that one more useful MANUAL control in the car stereo would be what I call the "loudness" control. It would diminish the loud pasages and amplify the low passages. Turned all the way up, the volume of all music would be the same. Turned all the way down, the volume would be unaltered from the recording. The Toyota has a version of this which does not work very well. It has a promising name, ASL, which I think stands for Automatic Sound Level. The problem is AUTOMATIC. It boosts the soft pasages and diminshes the loud pasages, but the degree depends on the speed of the car; the faster, the more severe the adjustment. The problem is that the adjustment is not enough at any speed.
Interesting, Michael. For most popular music this is already covered by the recording process. It is probably only classical music that would require equalization between loud and soft passages. As for classical, it never occurred to me to equalize loud and soft. Seems like that is something I'm not supposed to mess with.
I have a 2004 Toyota Highlander. I find the automatic climate control as fairly intuitive and acceptable, but really no advantage over a totally manual system. The real disadvantage is when I ever will need to trouble-shoot it for repair. More complex, more to fail, harder to trouble-shoot for a repair.
The older automated climate controls were much more clunky and sometimes providing heat when you wanted A/C and vice versa. I am mainly talking about the old GM "Comfortron" and Ford automaticly vacuum controlled systems. I do not like them.
I also prefer the old radio controls that you could operate by feel, and not need to look down to see which of the 12 to 24 tiny buttons you are about to push. The remote steering wheel controls put some of the intuitive back into the control. For example: I drove a BMW 945 one time without having the owners manual. It was hard to figure out how to start, put in gear, or open the gas door. I never tried to get the voice command radio and navigation system working. I'm sure it would have been nice after learning the systems, but was a little bit of a nightmare without an owners manual; even though, I consider myself pretty savvy about cars and technology.
Even in industry, I prefer any control system that is more intuitive; rather than, some computer-interfaced system that requires a week with the operation manual to learn the software, firmware, operating modes, and special features. For example, some of the features are imbedded in the codes, accessable by holding on the right pair of two buttons for over 5 seconds to switch menus as indicated with a two to four alphanumeric code on the display (defined in the manual). This requires a review whenever you go back to the old equipment and heaven help you if the manuals are lost.
Good points, David. Unfortunately, the nightmare scenario you describe is becoming more common than the simple, intuitive controls of the past. I many cases, this added – unintuitive -- complexity doesn't seem to deliver additional value.
This "feature" was designed just for you. My only complaint with the whole thing is it really didn't work that well. yes it got louder when I went faster and it got quiter when I went slower. But that whole how much louder/how much quiter thing, I believe it pretty consumer specific and I don't know if any car software can adequately provide a feature worth it. Of course, that's just my opinion based off of a 2003 version of the feature.
Wow...a lot of stuff being said. (How did the discussion get to audio anyway? Actually, automatic radio AVC is a pretty good thing since the noise increases as the speed increases so putting in some compensation is an obvious enhancement.)
Anyway, to address the ATC. I believe some people are missing some of the primary factors in these systems. First, car manufacturers all warn against using recirculated air in the winter since carbon monoxide leaks into the car interior (caused by things such as pinhole leaks in the exhaust or exhaust pipe imbedded in a snow pile) would not be diluted by a constant stream of fresh outside air, not due to worries about seeing one's frost on their breath! And, engines run poorer in cold weather emitting more pollutants and people often run their engines in cold weather when sitting still to keep warm, all making the need to flush the interior with as much fresh air as possible essential.
Now about the air conditioning...the biggest problem with cooling a car interior in the wintertime is not getting cold air out of the evaporator. It's cooling the interior mass which radiates heat to the occupants. In recirulation mode, they can focus on trying to maximize that mass cooling but at some point, they must switch back to fresh air intake for the above reason-to prevent carbon monoxide and other pollutant buildup. Also, in every car I've owned over the past 40 years, the air conditioning in recirculation mode stinks probably due to the recirculation mode inlet path stale/moldy panels. I use recirculate (Max) only when the outside is really hot like 105 deg or the like and the AC is struggling.
About fan speed, the one writer who complained that the air won't come out as cold, that's true but they're forgetting that air speed over the body is a very important factor in keeping cool (evaporation), almost as much as the temperature, at least in the beginning. That's why we sometimes use fans in our house and in the used max fan speed in our pre-AC car days. It also accelerates heat transfer, i.e., cooling down the car interior.
Actually, I don't like ATC for a completely different reason. On very cold days after scraping the ice off the windows, and otherwise being cold, once I get the car started, I like my system to 'overshoot' in temperature to warm my hands/body OVER and above the set point that I ultimately like. ATC's do not do that, they linearly or assymptotically approach the set point. Same thing on the opposite side with AC. After hiking or otherwise being really hot, I want to have max fan, max cooling for quite a while until I'm comfortable, something the ATC can not compute.
By accident, I discovered that disconnecting the 'aspirator' in my previous car's ATC, it reverted to manual mode and I left it there for the next 15 years! It's a gimick that maybe works well in mild climates or those whose cars are always in garages.
glad to read this one, a lot of good info here. I remember when I had problem with AC and my mechanic told me I had to replace the blower motor so I purchased one from jcwhitney's site... this is where I get cheap auto interior parts for my Toyota Corolla.
Ann you are so correct. I guess I must just be old fashioned, but I prefer to be able to control things by myself. If I want to recirculate the air I will and I do not feel the need for something making the decision for me. I also prefer single function knobs and buttons. In my wife's vehicle we have an aftermarket, Sony, radio.
When I want to change the volume heaven help you if you inadvertently push it in. It then adjusts the bass, push again for treble, again and it is now balance, and the next push takes you to fade. It takes a fifth push to adjust volume and you just have to pray you do not hit a bump or you get to start the cycle all over again. I know there must be someone somewhere who thinks this is cool, but I surely do not know why.
Ah, Tool Maker, that's a perfect description of how a lot of these electronic systems work. The funny thing it, if you really do want to adjust the bass, treble or balance, you have to spend 45 minutes with the owners manual. Twice a year I have to get out the owners manual to change the time. It's a series of about eight moves, all of which are counter intuitive.
Tool_maker, your description of those stupid tiny sound control buttons in the car's dashboard is very funny. I gave up--I adjusted them years ago and left 'em. So Bach, Beethoven, Segovia and Metallica all have the same settings. Oh well.
I don't see how wanting to have more control and less automation makes either of us old fashioned. Not all changes make sense. Just because we can change something doesn't always mean we should. And in this case, it doesn't make sense, but sensor makers are making a bundle.
Ann "just because we change ..." That is the perfect setup for this totally unrelated story. We have been using an old version of AutCad (14) which we could not load on the latest version of Windows, so we were dragged kicking and screaming into AutoCad 2012. We also replaced our plotter. We had trouble getting our plots to size on the roll of plotter paper.
The plotter guy said it was a CAD problem and the AutoCad guy said it was the plotter. We made an appointment when we could all meet on line and/or in person. The day came and when I had dialed in the offsite guy to my computer I brought up a drawing in V 14 and gave it the plot command. I was offered (15) sheet sizes plus user, which I could define as 36 x any length. The drawing plotted and then cut off 1/2" after the last line. Which by the way was the same way it was done clear back to V. 11, when I first started using AutoCad and the default scale is 1:1.
I then opened up a drawing in V.2012 gave the plot command and was offered (62) sheet sizes plus any custom size I choose to define. The plot uses the entire sheet, regardless of how small the plot is. I discovered this when I walked out on a 30 inch plot to find 150" peeled off in the basket. On top of that the default is now "plot to size'. So if I forget to enter 1:1 it plots whatever it takes to fill the sheet length and truncates top and/or bottom to accomplish this.
I told the AutoCad guy I wanted to set my plotter up like it was in V 14 and was told that I had to define each and every sheet size anytime I wanted to plot and to specify the scale. I have drawn dies as short as 6" to longer than 120". I do not want to have to continually redefine sheet sizes, so I asked, "How is that an improvement?" The answer, "I didn't say it was better. I just said it was different."
I really am not against change, but I object to stupid changes for the sake of change.
Tool_makerAutoDesk has become so big you can't even find someone to talk about your problems or make a constructive suggestion. It seems many of our USA public owned companies, public utilities and such now believe they don't need or want customer input at all. In fact certain company web sites don't even have a contact phone and use only FAX or email.
While I was in San Antonio back a week or so ago the SA TV news was exposing CPS Energy spending PUBLIC MONEY on lavish dinners and $200.00+/bot. wine for executives and guests.
My point is we have a deteriorating system of responsibility and ethics here and arround the world which needs to be adjusted and restablished to fix these seemingly minor problems that are slowly eroding our confidence and life style. The CUSTOMER NEEDS TO BE HEARD! The PROBLEMS NEED TO BE FIXED! CORPORATE AND PRIVATE companies NEED TO BE HELD ACCOUNTABLE for BAD PRODUCTS, BAD WORKMANSHIP, & BAD DESIGNS! In your case the BAD SOFTWARE you just paid for!
Autodesk reported revenue of $592.4 million. The 17 analysts polled by S&P Capital IQ predicted net sales of $583.9 million on the same basis. GAAP reported sales were 12% higher than the prior-year quarter's $527.7 million.
I agree, Ann. It's that old line, "Not all change is positive any more than all movement is forward." In the shift from analog to digital, there has been plenty of assumption that digital is superior simply because it's digital. A good example is the audiophiles who insist both the CD and the MP3 reduced the quality of recorded music. Steve Jobs was supposedly one of those stick-with-vinyl music lovers in spite of the iPad.
I probably shouldn't get started on the vastly reduced audio quality of MP3. Ecchh! I have a vinyl recording of Irish tenor Tommy Makem singing "The Wind That Shakes the Barley." It is the exact same recording as the one I later bought on CD. But on my 1987 excellent stereo with my husband's excellent speakers, the one on vinyl makes him sound like he's a few feet away from you in a club and you can hear his goosebump-inducing incredible voice doing that subtle tremolo thing. All of that is lacking in the CD recording, which I was surprised, and disappointed, to discover. That experience is what really made me realize how bad MP3 is, no matter which bit rate.
Yes, there's a difference. I hear it in acoustic guitar recordings. The vinyl has the warm hum, while the CD is crisp. From what you say, it sounds like the same problem occurs with the tremolo vocal. I would imagine it's the chunks of sound in the digital recording that hurts the warm sustained sound.
Yes, digital chunks. Neil Young has long complained about this. He insists digital recording can't capture the sound of an acounstic guitar accurately because there are a gazillion digital breaks in the sound. Some say the human ear can't hear the fact that digital sound is made up of pixels (just as we can't see the dots in color printing). Young disagrees. He insists you can tell the difference between pixelated music and the sustained sound of alalog recordings.
Another Neil Young fan! Yes, I've heard him complain about digital sound, but not at that detail level. I can definitely tell the difference. Those who say humans can't obviously can't themselves and may be working with averages, not the total Bell curve population that includes extreme outliers. If I could afford it, all my sound equipment would be older-audiophile stuff. OTOH, I think some classical music sounds a lot better on CD, especially strings and harpsichord. I can also tell the difference, although it keeps getting harder to do, between digital and analog photos.
What the human eye and ear do perceive, aided of course by the brain, is the Gestalt, the total picture or sound cluster, even if they can't perceive the discrete components. Theoretically, higher sampling rates would remove much of the choppiness.
Most of my music listening is in the car. I have music on in the house, but it's on while I'm working, so I don't listen closely. In the car, CD technology was a major improvement over tape. So, while I understadn that vinyl is superior, I don't get a chance to listen to vinyl often.
I am only an electrical engineer, but it seems the right logic to me. Each pass through the refrigeration unit drops the temperature by say, 10 degrees so it seems to me that you can achieve a much lower temperature and much quicker than by trying to cool air at a fixed temperature from outside. Aslo if the air is humid you can remove that much more moisture by working on the same air volume repeatedly. That is how I find it most effective.
Later when cool, the switch to fresh air is necessary to allow oxygen into the cab. Secondly the air is cooled in a small percentage in comparison to the volume of the cab so th A/C can cope, but my experience on really hot days (95degF and up) is that it only really maintains the temperature at a low enough value on recirculate.
I would also be interested in the fan speed that Toyota chose. It seems to me that the air conditioning is less effective at high fan speeds. My theory is that the air does not get enough time to cool down as it passes through the refirgeration unit.
From my experience the external air in the cold is to reduce the misting of your breath. I have a problem when I don't drive very far and the car hasn't had a chance to warm up where the air condenses and then freezes on the inside of the windshield.
I have been complaining about the stupidity of late model car environmental controls for 10 years now. I have sent detailed "bug reports" and fixes to the manufacturer only to be told that "the system is operating as designed". Obviously the problem is that it was designed to spec without actually being looked at from a systems viewpoint.
One pervasive fault is the divergence from older manual eviro control functionality when applying microcontrollers to the task. Older cars would handle defogging by running the AC compressor until the coil temperature approaches the freezing point where it would then cut out. When defogging, it's critical that the compressor runs no matter what the cabin temperature setting is. Late model cars have the AC compressor tied directly to the cabin temperature setting and sensor. This causes the humidity that was captured during cool down to start evaporating back into the cabin as soon as the cabin hits its target temperature. Stupid. Period.
The old method of running the compressor, condensing out humidity, while heating is the most effective way to deal with the situation. Instead, because the new systems perform so poorly, they do things like switch to outside air to try to make up for a poorly thought out design and implementation.
I agree-the logic is correct, for the reasons antedeluvian elucidated-even though his name is mis-spelled.. Humidity control is one big reason for recirculation when beginning the process, as it is much easier to cool dehumidified air than humid, and less humid air doesn't feel as uncomfortable, leading to more comfort sooner. This also is very important to defog the windows quicker in cooler temperature situations. For the technical Luddites, there is always an override capability. Undoubtedly, elements of their blood lines flamed the demise of manual spark advance and want it back! LOL
In winter I have passed cars with every window fogged up. I use the outside air setting in cold weather - I guess the occupants of the fogged up car didn't have an experienced driving instructor. In summer, I open all of the windows and set the A/C to outside air initially. After the hot cabin air, and the hot air in the vent system, is flushed, then I change to recirculate.
I agree with the final comment that the human has better reasoning than the canned program.
Repeatedly cooling recirc air is the quickest way to cool the cabin. (Almost all A/C systems pull-down tests are done in this mode.) Blower speeds usually start on high and step down as the cabin temp approaches the set temp, eventually settling on a lower speed. If and when to go to fresh air mode depends on the outside temp and humidity. (Note that most recirc modes do include a small percent of fresh air.) If your trip is long enough and the cabin gets cool enough you may even get compressor cycling to prevent the evaporator coil from freezing. (Ever have mist coming out of the A/C vents?)(Driving the first few minutes with the windows rolled down about 2 inches will let the hot air escape and improve your cool down time.)
If you have manual controls the first few minutes of heat up can be in recirc mode. (Say when your scraping ice or just warming the engine.) Once you start driving it should be set to fresh air to prevent breath and moisture from fogging the windows. Defrost should always be in fresh air mode with the A/C on. (The A/C will only run if the outside temp is high enough.) Some vehicles with inadequate body exhausters will fog the windows in cold weather regardless. I find cracking a window can help clear this up.
I would expect modern automatic climate controls to be well thought out and tested. The logic used has tradeoffs like every engineering endeavor.
I know some trade secrets and prefer manual HVAC controls, if available.
Are you sure the industry pull down test does not just apply to the lab environment and not the real world. If you are pulling hot air from the cabin in recirc mode, the air will never be as cool as outside air. Consider a winter day in sunny California. Air temperature is very cool, but trapped heat inside the car is hot. Openning the window is way better than any A/C.
The only exception is if you direct cold air to the floor. Air intake for A/C is near the floor. That way, air intake gets cold air and makes it even colder. With A/C at max fan, air gets very cold. Not sure if Toyota does that.
That brings another point. Fresh air from outside has to pass thru a hot firewall before reaching cabin. On cheap cars, there is no insulation on the firewall. You end up getting warm air from outside. If the firewall is well insulated, many times, A/C is not even needed. Also, with old vent windows, A/C is rarely needed.
The industry tests are done both in the lab and field. 110F ambient with 140F interior soak temp and solar load, usually at idle. (This is the worst case for A/C.) The recirculated cab air cools every time it passes through the evaporator. Cooling the same air over and over again will get it down pretty low quicker than continually drawing in 110F air.
Manual system engineers will usually only test hot temp A/C pull down, cold temp windshield defrost and cold temp heat up. If it can handle those the driver can make anything in between happen.
Automatic system engineers will test a range of conditions. But there is a time and budget limit. Your winter day/hot interior condition is common enough that it should be something they account for. But then they would have to predict how cold a winter day it was and how long the interior has to heat up and how hard is the wind blowing. So they compromise and the driver wonders why the system works counter-intuitively.
Ask 10 people what comfortable is and you will get 11 answers. HVAC system engineering is an art and a science that usually doesn't please everyone.
Some of the other posts have great tricks to improve HVAC performance.
I still would like the opportunity to actually control the recirc function. Sometimes there are reasons why you might not like to have outside air used. Smells, dust, etc. I had (note, had) a Chevy Trailblazer that would allow me to put it in recirc mode, but it would automatically reset to non-recirc mode every time I turned the A/C off and back on.
I live in southern California. It gets hot here during the summer. Recirc would be nice to have. My new Dodge Challenger has the same situation in that I can't control the recirc mode unless it is actually in 'cool' mode.
I can understand your point about removing humidity more easily when in recirculation mode. And I understand that keeping the cabin in recirculation mode when it is cold outside can cause misting. I've never been able to see my breath, but I have seen condensation on the windows; but it disappears immediately if I turn off the recirculation mode. I run into another annoying situation that I did not mention in my submittal. When it is cool outside and comfortable in the cabin, I prefer to keep the A/C off and keep the cabin cool with outside air. I find the air to be uncomfortably dry when the A/C is on and it is not very hot. I may drive like this for a good while and be comfortable. However, inevitably, I begin to feel very warm and sticky. It is then that I notice that the recirc mode automatically went on. I presume that this happened in response to a small rise in cabin temperature. Instead of increasing the fan speed to bring in more cool outside air, the system now recirculates the very warm air. I could understand that this would improve cooling when the A/C is on, but it does the opposite when it is off.
This "problem" is not isolated to the HIGHLANDER. It also rears its ugly head in the CAMRY. It's ironic when reading this blog, and the comments that follow, that one should take note of the recent TOYOTA radio advertisements that have been running for several months in my local market........ The 2012 TOYOTA CAMRY..... THE MOST TECHNILOGICALLY ADVANCED CAMRY YET!
Woe is me! I wish I still had my 2006 Camry. It was relatively simple; I could adjust the various control functions myself, all WITHOUT the aid of a microcontroller or two. My 2010 CAMRY replacement can't hold a candle to the 2006 model! I shudder to think of the next time I'm in the market for a replacement.
Wow. Guess I'll hold onto my 2002 196k mi. 5-speed manual Camry. Only issue with cabin air selection is automatic cancellation of recirculation mode when main selector is changed. Pulling outside air in during a rainstorm in Houston is counterproductive, so I always push the recirculate button again.
@VIRAGOMAN: Tampa / St. Pete / Clearwater area ain't no joy when it comes to HUMIDITY either! So, I feel your pain!!!
By the way, this 2010 CAMRY is SO smart that when you turn the dial for max. COLD on the TEMP knob, it automatically puts the A/C on in RECIRC mode, whether you want it or not! But, when you turn the knob a little to the c.w. position, it does NOT turn the A/C off. You must then press the center of the other knob to turn it off. There's so much about the 2010 that I dislike, it would take a tome to describe all its "wonderful" engineering enhancements!!!!!
With all of the great logic that we are talking about I can't wait to let my car just drive me to work. Sign me up for that. For some reason I see my 35 miles trip to work taking an hour and a half as I go back and forth throught the one way road maze of downtown nowheresville.
I agree, ViragoMan. Reminds me of electric windows. While I greatly prefer electric windows to manual crank windows, when the battery goes, the electric windows don't work. There are moments when a manual crank window comes in handy.
Makes sense to me. From a human standpoint, dry 90 degree air is more comfortable than humid 80 degree air. Thus re-circ passes cabin air repeatedly over the coils to remove humidity. Once the air is releatively dry, outside air can be brought-in dehumidified and cooled. For winter, when in re-circ - cabin air picks up moisture from the occupants and floor mats and is then re-directed against the cold windows creating frost. Taking outside air in winter draws in dry air which is heated and circulated. Well designed climate control in high-end cars blends cooled and heated air and keeps cabin air circulating continuously, they sense humidity, inside/outside temperature and adjust the controls as necessary, less well designed "temperature control" systems either heat or cool only and when the 'set' temp is achieved, the fan shuts down or goes to the lowest speed thus cabin air movement virtually ceases. There is a reason Mercedes cost more than Toyotas.
"Taking outside air in winter draws in dry air" - "Dry" is not a word used on the West coast in winter. These systems need a manual mode that is truly manual.
That's why one-size-fits-all 50K lines-of-code programs that operate 20 different computers don't fit all cars sold everywhere in the world. Just imagine how enjoyable it'll be to drive a car with radar speed/distance sensing when driving in a very wet heavy snow or getting slush thrown onto your front bumper while passing a semi. Slamming on the brakes at 50 with no warning should certainly enhance safety on the interstates. Probably work on in Southern California though.
One reason I like Apple products is because as an engineer, I hate half baked products features just to sell.
Looks like Toyota only designed for condition with the car parked in a garage with temperature same outside as inside. Toyota definitely need to spend a couple dollars more and install an additional temperature sensor before they go full auto climate control.
For me, the only thing that needs to be auto is cycling the A/C button on and off to reach right temperature. Leave all the rest manual. However, given majority of population, might be better off auto.
This is just another reason why I buy domestic. My 2005 Silverado crew cab heats & cools like a champ. In South Georgia where is gets 80 in Feb. with 60% humidity and 100+in July with 100% humidity, I need something that will heat me up quick & cool the same way.
From what I read, and after thinking about it, I think the automatic system by Toyota is correct. Toyota would be liable if an automatic HVAC system needlessly fogs the windows.
I've found the best way to cool-down the inside of a hot car in the summer is to roll down the windows, drive a mile or so to clear the hot air from inside the car. My wife always rolls down the windows of her 2007 Acura TSX using the remote control, so it's already cooling-off inside by the time we enter the car...nice feature!I keep my car windows cracked during hot and sunny weather to avoid the inside from getting too hot (and to help protect the leather interior).
I've also experienced fogged windows just after getting into a cold car during the winter. I found the fastest way to clear the windows is to drive with the windows open about an inch for a mile or so, then close the windows and crank-up the heat.
Sometimes people cannot be totally comfortable all-the-time despite modern technology...so we just have to live with it! It also takes time to cool-down or heat-up homes that had the HVAC turned off...not immediate comfort.
To avoid frosting or fogging up the windows, THE A/C MUST BE ALWAYS TURNED ON IN DEFROST MODE OR ANY COMBINATION THAT USES THE WINDSHIELD VENTS!
That is the option that gets the car company out of lawsuits for " obstructed vision " that causes accidents.
I know it looks silly on first glance, but anyone who has scraped off ice ON THE INSIDE OF THE WINDSHIELD knows why this is done.
The side effect of chilling air in the A/C is condensation, just look under a parked truck or car at the mall to see the pool of water underneath. I had a third party installed A/C in the motorhome that would freeze up in les than 10 minutes on a hot, humid summer day. Shutting off the A/C for the same time " defrosted " the thing....
Remember, there might be solid engineering behind some silly looking observations
I would agree with toolmaker about the difficulty often found with prematurely released operating systems. That is why I have not chosen to purchase the latest version, which offers no benefits that I would choose, and a lot of changes that I absolutely do not want.
The heating and cooling systems in cars all seem to be competing for an award for being "the most automated and command anticipating of all", with more features that anyone else. How else could the expense of a microcontroller possibly be justified? What makes it far worse is that the interlocking of functions has been done by somebody who seems to believe that I am too stupid to understand what I want to do. I agree that the choice of inside or recirculated air should be available at all times and for all modes, and likewise the choice of heating or cooling. I had those choices on my 1976 Dodge Aspen, and they were able to provide exactly what I wanted all of the time. All that in a car that cost less than $6000 new! The only change that I consider to be worthwhile in my newer Dodge Caravan is an option to be in the cooling mode with the compressor off. INstead there is a whole computerized system that is much more complex, probably has a hundred times more parts, and would probably be very hard to repair if something failed. Twenty blower speeds may be a bit nicer than three, but I would prefer a blower that only ran the speed that I set it at, instead of deciding what it wanted to do. And I am certain that it added quite a bit to the price, as well.
That's a great story. It reminds me a bit of some of the changes Microsoft made to Word way back when, and also of some really stupid, totally non-untuitive things about figuring out how to print stuff in Excel.
I've seen way too many dumb changes for the sake of change. Many of them were in the semi industry, which I used to cover. But many of them were in hardware and software I actually use. In software, usually they are just for the sake of releasing another rev since that's what the company's business model says it must do. I remember when Word was a great tool for writers. It hasn't been in ages. Microsoft is an easy target for complaints about stupid changes--but also a deserved one. There's something inherently wrong about a business model that says you have to keep changing stuff, even if those changes don't make sense, in order to charge the customer yet again to stay in business.
Speaking of backwards climate control systems, my ongoing litany of complaints about my 1980 Dodge with the deep-dish steering wheel (I can't remember the name of the car, but deep dish wheels were on a bunch of Mopar products...too boat-like for my taste) included a climate control system where the cable connect that temperature control slider on the dash to the air mixing box underneath snapped. So to go from warm to cool and back again, I had to reach under the middle of the dash and move a vertical half-wheel back and forth to get the temp mixing door to open or shut. A fun thing to do at speed, though I got pretty good at it.
I fully agre that the older radios did indeed have all of the controls needed for a normal person to be adequately entertained in a car. After all, we are in a car, not an audio listening room. I have no expectations that they should sound the same.
Now, about the inflexibility of selecting outside air or recirculated air: I have heard that STUPID carbon monoxide litany for many years, and I have never known anybody who parks their car in a snowbank with snow plugging the exhaust pipe that is full of pinholes. MOst of my driving is not done while parked in a snowbank. At 35 or 55 MPH, most of the CO that arrives inside my car comes from the vehicles ahead of me, rather than my own vehicle. So the real truth is that the auto companies are inflicting on all of us a measure included soley to protect them from being sued by stupid people. So at least they should tell the truth about why they do things like that. Of course, presently it is hard to find a car with the simple HVAC controls, unless one looks at a cheaper import.
REgarding the one post about the problem with the broken cable, those cables were fairly simple to fix and also fairly simple and cheap to replace. And if one did not mind things not matching, universal replacement cables were even cheaper.
Carbon monoxide IS a serious issue with many people being overcome by high concentrations warming up cars and/or idling with the tailpipe obstructed.
Even when driving, Mr. Bernoulli comes into play. I had it happen to me years ago with bad body shop work leaving a small gap in the trunk lid seal where it sucked in tailpipe fumes that we could smell.
What sort of conspiracy do you think all the world's auto manufacturers are trying to pull on us? They're just covering themselves by using as much fresh air as possible. As you say though, that's only as good as the air polluted by the cars in front of you but hopefully that's diluted a good bit.
The mechanical systems were balky, the vacuum systems were complex and expensive. The electronic system is current technology and once they shake out the bugs, hopefully will work for years, ATC or manual.
I agree with the poster about the multitude of tiny buttons. How many people have to die in crashes just so the kids can have their gadgetry?
This control problem can be eliminated if the outside temperature is known to the temperature controller. A simple compare of inside to outsiide temperature will make the cooling or heating algrithm simple.
The Toyota Highlander does have an external temperature sensor. In fact, you can pull up the temperature that the external sensor is reading on the display of the climate control system.
I don't think the system is behaving differently than intended. I think a lot of this discussion challenges whether the way that it is programmed is most appropriate or not. As with most engineering systems design, there are trade-offs and some different opinions on how those are best managed.
Naturally, in a fully manual system, those opinions become moot, because the user can operate the system the way they want to.
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