I can’t fully explain why, but for whatever reason, certain air-cooled Porsches seem to have the most needlessly convoluted HVAC controls. This is surprising because, as far as HVAC systems tend to go, the ones in older air-cooled Porsches aren’t especially complicated. Like their air-cooled ancestors, Volkswagens, the heating and defrosting system is mostly just a series of cable-actuated flaps that guide and direct fresh air heated through the engine’s heat exchangers. It’s not exactly rocket science. And yet, somehow, I think Porsche managed to make, in the case of the heating and defrosting controls on the one-year-only 1976 Porsche 912E, the most convoluted and needlessly baffling defroster/defogger controls the world has ever seen.
I’m genuinely impressed by the achievement; I think the 912E is unique among all automobiles in that it has a windshield defroster setup that would, at least for a decent period of time, baffle almost any driver, from any point in automotive history and any part of the world, even accounting for translating the surprisingly ample amount of text involved in the controls. In our modern era of HVAC controls that tend to have dedicated windshield defrost buttons or positions on a dial or even icons on a touchscreen, this may seem hard to conceive, but I’m here to show you exactly what I mean, so you can feel the same awe and wonder that I do.
First, to fully appreciate the madness of the 912E’s defroster controls, let’s just get some control samples out of the way. We’ll start with how defrosting/defogging happens in a huge number of modern cars – and I’m being really generous with “modern” since this basic method started in earnest in the 1980s. This is the “three knob” method, one that uses one knob for fan speed, one for temperature, and one for where the air blows, as in on your face, feet, or directed at the windshield, to defrost/defog it. The little “snakes slithering up a fan” icon is normally used for this. Here is this basic setup, as seen on the Slate pickup:
Okay, so that’s a relatively modern way. You want to defrost the windshield, you crank the heat and fan, and turn the dial to the snakes on the windshield icon. Easy!
But let’s see what some setups closer to the 912E used, as in other maybe air-cooled car setups, because those were always, let’s be honest, a little weirder. My Citroën 2CV, for example, is a bit odd, but not really difficult. There’s one funny little lever for how much heated air is coming into the car, and then there’s a little ball-topped rod you pull or push depending on if you want that heated air directed to the cabin or 0nto the windshield:
The volume of heated air lever is the thing in the upper right, with the red and blue circles. Closer to red is more heated air, blue is just regular ambient air. Pull the black ball back for windshield defrosting, push it forward for cabin heat. It’s a bit odd, but pretty simple, really, and I’m using this as an example because, fundamentally, this is all that the 912E’s HVAC system is doing, too.
Let’s look at how a VW Beetle accomplishes the same thing, because it’s similar:
In the Beetle’s case, there’s one lever between the seats for the volume of heat coming into the car, and another lever between the seats to direct that air to either the vents by the windshield or on the floor of the cabin. Really, the same thing as the 2CV, just with a different placement of levers. If we look at the more up-market VW Type 4, the car that actually donated its engine for use in the Porsche 912E, we see a bit more complexity, but mostly just because the Type 4 has a more advanced fresh-air ventilation system and an auxiliary gas heater with such nifty features as a timer you can use to pre-heat the car on cold mornings.
Even so, the basics of windshield defrosting aren’t really different than in a Beetle:
Looking past all the ventilation and gas heater stuff, if you want hot air to melt frost or clear fog from your windshield, you’re still pushing that DEF/HEAT lever to the DEF setting. That’s pretty much it!
Okay, so we’ve seen what these close siblings to the 912E ask of you if you want your windshield defrosted; let’s see what the 912E herself demands:
Wait. What? This is the part that gets me:
“DEFROST: MOVE UPPER LEVERS LEFT, LOWER LEVER RIGHT.”
Something about that sentence just takes a moment to process, at least for me. If I was driving and having trouble seeing out of my windshield, I don’t think I’d be able to grok it any quicker?
Okay. So, the red lever – which I think is for the volume of heated air coming in, which is sort of like temperature, in that it mixes with ambient air, in this case needs to get cranked all the way up to full heat, because it’s the lower lever, and the upper two levers both go all the way left? Okay, but that seems to mean the fan gets turned off, which I don’t understand why that would be, and then that makes me realize I don’t really know if it’s the middle lever that controls the fan or the top one, and whichever one it is, I’m not clear on what the other lever does?
Is the middle lever like the defroster/cabin slider? I think it may be, though the markings and position all make it more confusing. There are up and down arrows at each end of these right-to-left sliders, and I think it’s DEF.MAX on the right and DEF.MIN on the left, but if that’s the case, then why would I be told by that sentence to move the upper levers to the far left? Wouldn’t I want the slider to DEF:MAX for maximum defrostery?
Or is the bottom lever, the red one that suggests heat, the defrost max/min lever? Because then at least I’d be told to slide that to DEF:MAX, which makes a bit more sense? But then what does the middle lever do?
This all feels like someone way overthought this to the point of madness. It shouldn’t be this hard! And here’s the amazing thing: Porsche seems to have kept this baffling system for quite a while: the same basic setup is used on 1980s Porsche 911s, just augmented with other air-conditioning controls and the traditional between-the-seats heat/defroster levers. This guy seems delighted to show you the weirdness of it all:
I think the 911 implementation of the strange 3-slider setup is less bad than the 912E because it (A) eliminates the confusing sentence and (II) it can be mostly ignored because of the other sets of A/C and heat/defrost controls? Still, it’s hilariously obtuse.
Now Porsche isn’t the only carmaker that has managed to make defrosting strangely difficult; look at what the Fiat Brava asks you to do before you can defrost your windshield:
Photos: Murilee Martin, in one of his junkyard excursions
The Fiat asks that you close the central heater outlets your own damn self so the air can get re-directed to the windshield. It doesn’t really have any separate defroster controls at all, just six words that tell you how to make defrosting happen. That feels pretty lazy, but at least it’s pretty straightforward.
The Fiat’s cousin, the Alfa Romeo GTV6, is sort of similar; while it has a setting for defroster (slider all the way to the right, by the universal snakes-on-a-fan icon), it also takes the time to note that if you want MAX DEF (which I think just means either the defroster actually doing something or, less likely, Mos Def’s older brother) then you need to close those two central vents yourself.
A slight step up from the Brava, still not great, but still fundamentally understandable.
Either way, these are both a million BTUs better than the Porsche 912E setup which, I’ll be honest with you, I’m still not entirely sure I understand. If we have any 912E owners reading this, I’d love to know more: how exactly do you get your windshield defrosted? I really like 912s, even the odd US-market-only, one-year-only, VW-engined 912E, so please don’t consider this a slight. If I had a 912E, the baffling HVAC controls would be one of my favorite parts of the car, and I’d ask everyone I gave a ride to please, if they wouldn’t mind, turning on my windshield defroster, just so I could witness that delicious moment of perplexity and confusion.
I bet it’s really satisfying to see.