Compared to modern cars the heating system on air-cooled Volkswagens might seem a bit antiquated, a critisism fuelled by the fact that on most cars it’s seldom working at its full potential. Yet when it was conceived all those years ago it was relatively up to date – and if everything is in place as Volkswagen intended, it’s actually pretty effective…
Sadly, what tends to happen as a car passes through various different owners throughout its life is that the system isn’t kept how it should be. This means the heating doesn’t operate at full efficiency, which is why people assume the heating is terrible! So here are the 5 most common problem areas and some possible remedies to get your air-cooled VW’s cabin roasting hot again…
1. Heat exchangers
On an air-cooled engine air is sucked into the back of the fan housing and blown over the tops of the cylinder heads to help cool them. Air from the fan housing is also blown via the two corrugated flexible hoses either side of the engine into the heater pods then into the heat exchangers. There is a pipe with fins cast over it running through the heat exchanger which exhaust gases pass through. These fins effectively heat the air inside the exchanger which then passes into the car. The problem is, there’s lots of opportunity for this warm air to escape via rotten heat exchangers so check their condition and order new ones if they’re past their best. Beetle ones are here.
2. Heater cables
The heater controls in the car operate a flap in the heat exchangers via cables so you’ve either got hot or cold air. The control flaps are spring loaded so if the control cable snaps or is disconnected they will stay shut preventing any hot air getting into the car. The most common cause of the heaters not working is the cables not being connected to the heat exchangers, this usually happens when the engine has been removed for any reason and the cables not reconnected when the engine goes back in. Cables and various other heater bits for the Beetle can be found here.
It’s amazing how much warm air can be lost if fittings are missing. We’re talking here about the various jubilee type clips that secure the cardboard covered flexible heater hose to the fan housing and the metal collars that fix the sleeve that pushes into the bottom of this hose to the heater boxes on the exhaust. The clips can also be missing on the short section of flexible pipe that goes from the front of the heat exchanger into the car. There’s also a section of pipe that runs up the A-post to provide hot air to the screen vent on a Beetle, so make sure these are all in place as well.
4. Heater channels
Once hot air exits the heat exchangers it passes through another piece of flexible pipework which takes it into the car’s heater channels each side. Now, we all know on a rusty car these can be the first things to go – and when they do, so will all your nice cosy warm air. The only solution is to fit replacements or weld up any holes. More often than not you will find the flexible pipes are connected to the heat exchangers correctly but without the seals in the ends causing air leaks and lack of heat. Buy replacement channels for the Beetle here.
5. Leaking exhaust
If you smell smoke, then chances are your exhaust has holed and fumes are getting drawn into your heater system. The effect will be even worse if the rocker cover gasket has allowed oil to seep out over the top of the heat exchanger. Thankfully, a new gasket only costs pennies.
A big thanks to Colin from Itinerant aircooled for the use of the fantastic illustrations above. Please check out his website for a wealth of aircooled fault finding knowledge here.
The opinions expressed here are the personal opinions of the author and do not necessarily represent the views and opinions of VW Heritage