Volkswagen Repair: auxlillary heater repair, volkswagen campmobile, inline fuse

Question
1978 volkswagen campmobile auxiliary heater will not work.  Checked 16 - 8 volt fuses, underdash reset switch but still will not ignite.

Answer
There was more than 1 type of auxilary heater type used.  I am familiar with the canister type (grey tubular shape in either the engine compartment or mounted ontop of the engine compartment(drivers side inside the vehicle)  There is another type that is mounted ontop of the transmission-no experience with it) So I refer to the canister type.

Does the aux. heater run(does it make some vacuum cleaner noise?)There is an inline fuse too.
 Okay, if it does, but you got no heat--would be first to check the glo-plug.
  Still no heat?   Well this type of heater works like a turbocharger-basically same parts.  On the one side there is an impeller that is driven by the heated gasses of combustion.  The shaft that impeller is mounted on goes to the intake side where there is another impeller(cold type) that draws in the cold air and blows it past the warmed combustion chamber before it re-enters into the van.   
  I have had one where the combustion impeller blew up(pot metal) shortly after purchase of the vehicle(from new) and never really realized it because never really needed it.  Parts are non-existant as there is no repair to be done on these things.  So the motor ran but it would not inject fuel into the combustion chamber--part of its safety features.  Weird but true.