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:
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:
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.
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:
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. But frankly, these days, as long as there are physical buttons I won’t complain. 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. Took me forever to figure out what that fog light setting was for — finally had to resort to digging out the owner’s manual. 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. 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.) 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. Interestingly enough, they do have a symbol https://www.iso.org/obp/graphics/grs/403a15bf-4eab-4e2e-bc50-69eea63d3f3d_200.png for “Windscreen (windshield), electrically heated” but it does not appear that they have one for the rear.
