I had a Golf  that had no heat one time.

The problem ended up being the heater core (gauge and thermostat were
working OK)

The heater core had plastic spirals inside the core tubes

 (that swirled the water for better heat transfer I guess)

anyway,  these plastic spirals were degrading, breaking up, and  stopping up
the heater core completely.

Not sure if these things are in all the VW cores but I have since seen them
in Radiators too.

Feel the lines going to the core is one hot and one not?

jeff

87' Westy "weekender"