Quick Question: Where Should The Rear Defroster Button Go And What Should It Look Like?

Wheredefog Top

I think of all automotive dashboard controls that can be considered among the standard complement of controls of a modern-ish car (as in, from, say, the 1980s and up), the one that seems to be the biggest vagabond, the one that seems to have resisted finding any sort of standard home, has to be the rear-window defogger/defroster switch. It’s also an interesting case where the icon for this feature has been standardized, but in a way that is conceptually wrong, at least based on how most of these work. I’ll explain.

First, think about the cars you’ve owned or driven, and think about where the various controls were. For most of them, there’s certain conventions you can expect: lights on stalks or perhaps dash knobs to the left (on an LHD car) of the wheel, indicators on a stalk, HVAC in lower center, usually below the radio, and so on. Now think about where the rear window defogger switch was on those cars. I’d bet David’s money no car had it in the same place.

Look, here are a few cars from the 1960s to 2010s with their rear defroster switches highlighted:

Variouslocations

Are you trying to find some sort of pattern or reasoning behind the switch placement in these? If so, I beg of you, do not, because that path can only lead to madness and pain. Sometimes it’s grouped with the HVAC controls, sometimes sort of near them, but not really, sometimes close to the driver, sometimes not, often they’re just slapped next to the hazard lights switch, clearly slapped there at the last minute in a panic when some quality control somebody was running down a checklist and realized something was missing.

That old Beetle had a little switch under the dash, completely invisible, even though the addition of an extra switch on that sparse dashboard would have made the car look decades more modern. Nobody knows what to do with the damn thing.

Personally, I think the sensible place is with the other HVAC controls, because it does a job similar to the windshield defogger, even if it’s not technically part of the HVAC system. And that leads me to the next mystery of the rear window defogger switch: the icon for it.

This is what the modern accepted look of the defogger switches are – on the left is the windshield, on the right is the rear window one:

Defogicons

So, we have the accepted three-planaria-wriggling-onto-glass convention here, though sources have told me the squiggly arrows are not snakes or flatworms but rather represent air blown from vents in the HVAC system. The front is indicated by the area cleared by a windshield wiper, and the simple rectangle is supposed to remind you of a rear window. Okay, fine.

But here’s the problem: for most rear window defoggers and defrosters (yes, there’s a few exceptions, usually ’60s vintage or so), that’s not how rear window defrosters work. They’re electrical. There are no snakes – sorry, no air being blown to clear the rear window off, it’s just a bunch of resistive elements (wires) in the glass.

Wires

When you’re actually using the rear defroster, you can see this very prominently. It’s warm electric wires doing the work, not blown air. And early defroster switches tried to convey that:

Oldones

See? Those all have icons like little resistive heating coils. They’re much more accurate about how the rear defroster actually works. But this icon is effectively extinct, replaced by the deceptive three-snakes air-blowing one.

Personally, I think the ideal is the old-style, more honest icon on a switch that’s grouped near the windshield defogger controls. That way, it’s got an accurate icon, and the location is grouped by the driver’s needs – get the windows clear – which seems to make the most sense to me.

I’m open to hear what you think about this vitally, possibly even gravely important issue! Let’s discuss in the comments! Hash this out, once and for all, and settle things.

 

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60 Responses

  1. Another switch without rhyme or reason regarding placement I feel is the hazard switch. I’ve had vehicles where it’s on the center of the dash above the audio system, lower down on a center console, or even on top of the steering cowl.

    1. I figured it’s some kind of requirement that they are on the dash now, usually large and obnoxious and clashing with the rest of the dash design.
      I always preferred the ones kind of hidden on top of the steering column because it’s a button I almost never use.

    2. Old school GM put it on the steering column. It’s probably because it’s what I grew up with, but somehow it seems that’s where it belongs, not too far from the turn signal stalk that most often makes the blinky thing happen.

  2. The really weird thing is when it has a different light than the rest of the HVAC controls.

    Personally, I like putting it near the seat and steering wheel heaters, because then I can tap all three at once on a cold day, but as long as its with everything else heat related it’s in the right spot.

  3. I too agree that the symbol should be represented as a resistor type icon, but not one too similar to the glow plug icon for diesels which is also shown as a resistor.

    As for placement I’ve always thought that VW nailed it with the MK4 Golf/Jetta dash with the defrost button prominently positioned to the right of the hazard button just below the HVAC vents in the centre stack. I like seeing it prominently displayed because it can remind you of you’ve left in on unnecessarily and are instead just wasting fuel.

    This is the same positioning as on my London Taxi where this button is crucial to being able to see out the very large back window. In the case of my taxi they even went so far as to install a timer relay that automatically shuts the defroster off after 20 min to conserve fuel. That’s real dedication for a late 80s early 90s commercial vehicle.

  4. Any time I drive a new-to-me car and I need the defroster, it’s a scavenger hunt across the dash. Agreed, it should be with the HVAC controls, but I wouldn’t overthink the symbol. Functionally it’s doing the same job as the front defroster, just in a different way, and most people aren’t thinking about coils and whatnot. Better to be consistent.

    1. Yep, the three planaria have become common usage for “defrost”, no matter how that defrosting happens. Sort of like how a floppy disk is still the icon for “save” even though no one has used floppy disks in a decade or two.

  5. I totally agree with you about the snakes/worms (which also reminds me of the little-known Samuel L Jackson film, “Planaria on a Plane”) and I agree that the symbol should be the representation of a resistive heating element. But maybe just lines across a rectangle, you know, how the defroster actually looks in real life. And the location should be close to the front defroster setting, like it is in my 2004 Tundra, which I’d post a photo of if I could. The ventilation control knob has the front defroster setting at the lower right end of the arc and just below that and to the right is a nice, large, clear button for the rear defroster. That’s perfect, in my opinion.

  6. What’s a button?

    Oh, maybe Jason means an ICON on the Magic Touchscreen….

    I’ve owned cars with rear defrosters, and their designers put the buttons with — or near — the HVAC controls. They had lights in the cluster, of course, and all had nifty timers so the defrost cut off just about the time the window was clear….

    Dang, I miss the Old Days.

  7. I’m thinking grouped with the heater controls is the best, and I’ve had cars with them almost everywhere except the glove compartment.
    Now what about heated mirrors and seats, should the switches all be in a row with nice icons?

    And who here remembers when US cars had optional heated rear windows and it was a blower unit with a electrical heater that dropped in the middle 6×9 speaker cut-out in the rear parcel shelf?

  8. I don’t care where you put it, because I don’t think I’ve ever pressed that button living in the south. Heated seats and side mirrors use the same wavy lines, but I prefer the look of the coils for all of them.

    1. I’ve used mine dozens of times this summer already, in the Florida panhandle. In fact, instead of an ice scraper, I keep a small squeegee in the car to clear the glass on mornings after it got below the dew point the night before. Foggy windows are a 12-month problem here.

    1. This 100%. I mean, when *isn’t* it horizontal lines? It’s literally what you look at in your rearview when you think “man, I can’t see, how can I fix that?”

      All I can think for the “why the wavy lines?” is most people no matter where they live are used to at least occasionally using the front defroster to clear condensation, so they make the mental connection for the other switch that they perhaps never used if they live in a hot, dry climate?

    1. Yep, I always considered the squigglies to be radiated heat, not explicitly air. In fact, I believe the ’97 Mondeo I drove in Scotland had a resistive mesh in the windshield rather than blown air from the dash for a defroster. As I recall, it work pretty well, too. I don’t recall the icon on the button though.

  9. I don’t really care where they put it, as long as there’s a button. Front + Rear Defrosters need to be their own buttons that you can easily press when you’re out in January and the glass starts fogging/icing over.

    You can usually tell which cars keep cold weather in mind when they design these things – they’re sensible and easy to reach. You might have to learn which switch is which, but they’re there. Then there are the cars that clearly aren’t designed with cold weather in mind, and they are clearly an afterthought. But at least they’re there.

    Then there are the cars that had them prominently (and confusingly) in the UI easily accessible at all times, only to bury them in a menu in a Christmas update making the car quite a lot harder to drive in the winter. THEN allowing customers to return the controls to where they should have stayed in spring when they’re not needed anymore. I will always be mad at Tesla for doing that.

  10. I find snakes a very impractical way to defrost windows, I don’t recommend it. It would be very hard to direct them to the rear window, and even then it wouldn’t necessarily defrost it. I definitely prefer an electrical defroster.

  11. First-gen Saturns had a toggle switch on the dash, behind the washer stalk and just below the gauge cluster. The icon was to the left of the switch and I think the defroster was actually on a timer.
    You can kinda see it here.
    https://consumerguide.com/wp-content/uploads/2014/07/91130011990120.jpg
    Frankly, I think this was ideal. It was near all the windshield-related controls but didn’t crowd up a stalk. Plus, you didn’t really have to take your eyes off the road to turn it on.

    What bugs me most about the HVAC location is that it’s usually farther down on the dash and next to the windshield defog button. It’s easy to mix-up the buttons, especially when you’re driving in weather that requires you to keep your eyes on the road and defrost the windows.

  12. On my first car, a Maruti 800, the defroster switch was grouped with all the extras (rear wiper and washer switch, thats it, it was a ’93 DX model) left and lower of the steering wheel (LHD). I always forgot which was which, and you had to look at it, in that hidden, inconvenient spot, while driving. Suffering from success.

  13. The wavy lines (or some like them) show up on the fog light control also — at least the do on my wife’s PT.

    Took me *forever* to figure out what that fog light setting was for — finally had to resort to digging out the owner’s manual.

  14. All those ISO standard icons are absolutely *awful* at their supposed job of clearly conveying information without the use of any particular written language. They are terrible, just terrible. It would be better if they were just English words, or hell, Portugese or Ukrainian or even fucking Esperanto or because then at least *some* people would understand them, whereas now they are equally incomprehensible to everyone. In fact, if they’re gonna make everything in cars a touchscreen, there should be an option to replace the stupid symbols with words in the language of your choice.

    Those dumb, dumb little symbols. Everyone on ISO Technical Committee ISO/TC 22/SC 39 Ergonomics should be slapped into a coma.

    Also, why have a button? Just have them come on for 15 minutes whenever the car starts up, if it’s below say 5°C outside. It’s not like they’re gonna burn out.

  15. It’s a symbol, not a pictogram. So it ought to be related to the symbol for the front defroster. But as a pictogram, it’s 3 devil’s tails. Everybody associates devils with heat, right? It’s 3 devils farting in the direction of the window.

    As to where, it ought to be with the control for the front defroster. (Mine is a button in the center of the knob that controls where heater air is directed to.)

  16. I knew a guy who had a circa 1995 Escort that came with a sticker on the console explaining to set the vent to the windshield position and turn on the A/C to defog. Probably a little wordy, and I don’t know how much literacy controls should be assuming, but it was unambiguous in a way a bunch of ikea guys might not be

  17. Re: what the icon on the switch should look like – I think we’re at the stage where folks have come to associate the current, “wrong” but standard, icon with the squiggly arrows with defrosting, so I say keep it. Just like the skeuomorph floppy disk icon meaning Save is likely not going anywhere any time soon, as anachronistic as it has been for decades to anyone not named Jason Torchinsky.

    That said, good things happen when Torch thinks established icons suck – I for one have fond memories of an article about the check engine light on the German lighting site – so by all means, Torch, propose a new design!

    Re: where the switch should be – thank you for allowing me to Sparkypost once again: I think that the M400 Chevy Spark has the best, most intuitive HVAC/HVAC-adjacent control panel ever – three evenly spaced, equally sized dials that double as buttons. The left one controls the temperature, the middle one controls the intensity, and the right one controls the vents. Pressing down on the left one toggles the AC, the middle one toggles recirculation, and the right one toggles the rear defroster. It’s a brilliant layout and I love it.

  18. Lets see, here. Just some examples from some of my current/past Fords. A wide variety from a single manufacturer. I have a pair of 2007 Focuses (Foci?), push button with the HVAC controls in the center stack. 1993 Ranger, nope! 2001 Mustang, push button in front of the shifter. 1995 Mustang, under the headlight pull knob. 2002 Windstar, push button with the HVAC controls in the center stack. 1995 & 1997 Aspires, in a row of (mostly unused) switches in the top of the center stack. 1983 Thunderbird, lever in the HVAC controls. I don’t remember the 1978 Fairmont having one. And my 1946 pickup is a rag on the seat!

  19. Something that used to annoy me, and for al I know it’s still a thing; domestic cars shut off the rear defroster, while Japanese cars keep them on. That is in a Japanese car, once you turn on the rear defrost it will stay on until you sell the car. In an American car (not badge engineered) after some time, or current sensor (??) shuts off the defrost, meaning at some point you can no longer see out the back and have to start the process again. These switches are different, the domestic ones being a rocker or button that is momentary, turning on the light and heating the wore, in Japanese cars the button is a maintained on/off.

  20. I don’t mind the wavy lines for the symbol. I mean, whenever you’re out on the road in sweltering heat, or you’re watching a movie about people crossing the desert or whatnot, you always see the wavy “mirage-like” light diffraction effect. I just always assumed those wavy lines on the button indicated “heat” and not “air blowing from a vent to defrost my window”. I don’t care about the method by which my rear window is receiving heat. I just know it needs heat of some kind. Wires, hot air, buffalo farts…who cares? Just apply heat.
    As for the location, it definitely just needs to be right next to the front defrost button, located with all the other environmental controls. Don’t put it on the door, or up on the roof panel. I’m not driving KITT here.

  21. I like how it is on our Subaru Forester, actually really like the hvac control layout, 3 giant knobs, direction, fan speed, temperature, rear defrost is a center button on the direction knob, recirculation a button on the fan speed, and ac a button on the temperature, just so simple and easy.

  22. The standard window with lines blowing works for me.

    Location? I like it be part of the Air Con system. In most of my cars it is in the blower setting. Click, lights up, done.

    Or in today’s world, on a 42 inch plasma screen attached to the dashboard, put in 15 levels deep under Self Destruct-Do not use menu item.

  23. The thing is: it doesn’t matter what exactly the arrows represent, if it is warm air or just heat in a more general sense. The effect is the same: no more ice/fogging on the glass, either front or back. Whether the effect comes from resistive wires embedded in the glass or from warm air being blown at the glass is of no interest to the driver. (The switches with the electric coil? That would be the “pre-glow” function on old diesel cars.)

  24. My first car, a 1982 Datsun 200SX hatchback, had the rear defroster switch in the center console next to the handbrake. It’s the only car I’ve owned that used that location. It was also a “hard” switch, meaning when it was moved to the ON position, it stayed there (and the defroster stayed active), until the switch was manually moved back to off.

  25. My 1968 Ford Galaxie XL had a knob down at the bottom of the dashboard marked Defog and a fan in the back deck

    Leaf and the BMW 850 both have the defrost buttons with the HVAC Controls

  26. I wish I could post a pic but I can’t. Look at the newer XC90s. They have an electric FRONT defroster in addition to the conventional one. The symbol is the same curved windshield, but with that resistor element in it, like the early rear defrosters. Funny thing is, the rear defroster still shows squiggles despite being electric.

  27. Definitely with HVAC. The icon can stay or could just be a rectangle with horizontal lines. I think people associate the current symbol with the similar function up front, so it works, even if it isn’t accurate.
    While we are standardizing, though, wipers and lights should probably get that treatment, too. Make essential functions like those easier for people to remember across vehicles.

    1. All Defroster controls should be with the HVAC controls. It makes a logical association with heating and cooling and distribution to feet, torso, face, windshield. As for symbols, use of the same “heat snakes” for front and rear makes the function of the button for the rear window defogger easier to understand. You get physical feedback from pushing the windshield defroster button and it’s easy to make the mental leap that the second button must perform the same function for the rear window. If you use a different symbol the first thought is that being different it must perform a different function (hell, glow plug maybe?) – and because the rear defroster gives no immediate feedback (no fan sound) it’s easy to assume that pushing the button did nothing for the window. Worse, it’ll be several minutes before you get any visible results.

      Sure, sure, the wavy heat snakes are not technically correct for the way the rear defroster operates but as a symbolic society we are way way beyond that level of literalness. I mean, look at the phone icon on your display. There is an entire generation now who know that symbol represents “phone” but have never seen or touched a phone receiver.

      And actually, here’s something I would like to see Jason pursue for us: the international low oil icon that looks for all the world like Aladdin’s lamp. How on earth did “they/someone” decide that everyone would recognize that as oil? I wanna know!

      1. I mean, it is an oil lamp, a thing we all definitely use in modern society. I don’t know what kind of weirdo thinks of that sort of lamp in the context of a few stories about genies.
        And, really, who doesn’t fill their vehicle with oil that they’ve been keeping in that oil lamp? Like you would buy oil for the express purpose of keeping your vehicle lubricated? Must be nice to be so rich.

  28. this is one of those few things that i could get behind automating. determining dew points and measuring temperatures of surfaces is childs play compared to lane keeping and the other garbage thats in cars. it should be tied to the automatic climate control, the rear glass should be kept above a temperature where dew/frost forms. there is no reason to hamper visibility because someone forgot to push a button. im reasonably sure this wouldnt even need additional sensors, as you could measure the resistance and/or current sense the defrost grid, and determine its temperature from it. if you have to have a button, put it on the consolette near the rear view mirror, since thats where you attention is going to be when you notice a problem.

  29. I think the current switch is good because it makes sense to a lay-person who doesn’t think about how defrosting windows works; I think the coils, while more accurate, would confuse Jonny and Jenny Leasing-A-2020-Honda-CRV would be like “WTF is this button” and “Where is the rear defroster??” during the winter months.

    As for location, it should be next to or near the front defroster imo

    1. I reluctantly agree – as much as I see Jason’s point about that’s not really how the thing works, keep in mind that most people are morons. The UI needs to be moron-proof, so I see why we’re going to end up with an icon similar to the front defogger, right on the HVAC panel next to the front defogger.

      My question would be “why is there even a button for this”? With all of the sensors on modern cars, can’t the car just detect based on the outside temp that the rear defogger should kick on when you start the car and maybe like every 30min thereafter?

      1. I would prefer the bacon coils if I were to do a clean-sheet redesign, since I like the way those look and it is more the best kind of correct. That said, the current truncated cone = front / rectangle = rear probably works pretty close to universally. I firmly believe they should be with the HVAC controls and I could see an argument for two contiguous buttons, the front/rear of a side profile car pictogram split in the middle, with an arrow pointing to the windshield on one and the rear window on the other. Or replace arrows with devil tails or bacon squiggles

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