How does the heater work on a 69 vw bug?

Answer 1

It Doesn't :).... because it's been neglected for years. beetle heaters are very good, the demisting isn't.

Cool air is drawn into the engine bay by the air-cooling fan. When the heater control flap is pulled (RHS by hand brake) some air flows over fins on the exhaust pipe that are encased in a box. These heat exchangers heat the air as it passes into the cabin. You can control where the air exits via the control on the other side. Down is for front, up for rear. Then you have flaps at the lower vent level.

Of course none of this works in your car if you haven't fixed it.

work from the back;

Check you have a standard exhaust with heat exchangers

Check you have good hoses from the fan shroud to the heat exchangers

Check your heat exchanger flaps haven't seized shut/open

Check you have cables attached between heat exchangers and controls

Check all hoses into the cabin are in tact.

If you get that far you should have heat to the rear, keep going with the flaps and hoses until it all works.

Because it runs of the exhaust pipe you get heat really quickly.