You really don't need to run the A/C during the winter, or at least
in the mid 80 and later VWs. If you notice on the heater controls
there are the three A/C settings and then the upper/lower and
defrost controls. The order was set on purpose so that everytime
you use the heater, you turn on the A/C for a few seconds and allow
the compressor to turn over. 

All you need to do is to have the compressor spin around everyonce in a
while in order to keep the seals lubed.

Ric