Myths & Rants, Part the First: In Which One of Ludwig's Drivers Attempts to Demolish a Bit of Conventional Wisdom about Air-Cooled Volkswagens

Myth: They're cold! 

Rant: Yes, they sure can be. But it wasn't always so.

Being air-cooled, old VWs don't have a reservoir of very hot water to draw from when it comes time to warm up the cabin. So what die Ingenieure did was build a box around a big chunk of the exhaust system. That box's purpose is to get the air it held really hot (courtesy of the exhaust piping) and send it into the cabin on demand. They're called 'heat exchangers' or 'heater boxes'. 

image cribbed from ratwell.com

Off the showroom floor, there was nothing wrong with this system. I spent a few Nebraska Winters driving around a friend's very nice 1971 Beetle and can attest that I was often turning the heater down. The earlier Type III's heaters worked so well that VW had to replace some of its plastic components with metal ones, as the plastic parts were getting melted by the heater.

image cribbed from some other place

So what went wrong? There're a few problems. One, if there are any leaks in the ductwork between the heat exchangers and the cabin, heat pours out like crazy before it gets to the cabin. Unfortunately, some of the ducting (in Beetles, Type IIIs, and Karmann Ghias at least) is routed through areas which are very much prone to rust. Two, if the car itself isn't sealed well, say because of rotten 40 year-old door seals or poorly fitting two month-old aftermarket door seals, heat is lost that way too (my buddy's '71 was about watertight). Most cars probably have a combination of these two problems. Compounding things, the problem is often magnified by greater expectations. That is, if you're the kind of lazy person who expects  to be able to adjust your car's heater to the degree, and by each area of the cabin, then you're not going to be satisfied by anything an old VW can offer you in the way of heat, or likely anything else. Get a Chrysler, and good riddance.

image cribbed from some other guy

In water-cooled cars, if you have a leak in the heating system you lose coolant and the car alerts you to this, one way or another, because a coolant leak will eventually kill it. In an air-cooled car, if you have a leak in the heating system you just have an anemic heater. Multiply this by millions of old Volkswagens rusting and leaking their way through the 1980s, 1990s, and 2000s, and you've got the making of a piece of common 'knowledge' on your hands. But the fact is that a properly maintained ACVW heating system works just fine.