Hello Subagurus.   1985 EA82.   Here is the story...

A few weeks ago, had been driving for 30 minutes - then the heater/defrost stopped blowing.

I only run the fan on high (4) because I want to save my resistor pack  (high runs at the full 12 volts).

  So I get home and find that the two 15 amp fuses for the heater have blown.  

  I replace the 2 fuses... all works well.

  Yesterday, I drive the Soob for about 10 minutes.  Heat was on, Fan was blowing set to high.... then stopped blowing.   So I figure the fuses blew again.

  Get home, sure enough, both fuses for heater were blown.

  I go to replace the fuses, and immediately when I insert the 15 amp fuse into the slots ... the fuse blows.    I did this twice, same result.    Key is OFF (actually sitting on the dash).   Heat Selection is set to OFF.  Fan is set to lowest setting.  

  This has me stumped.  Why would I be blowing fuses with everything off, no key?   Any suggestions on what might be the problem?

  I pulled the fuse block, and all looks good - no mice - no moisture.

  There is also a fuse for FAN - but that fuse has never blown.  Not even sure that runs the Heat/Defrost Fan.

Have you checked to see if the blower motor is shorted?

Check the connector on the blower motor itself. I had mine turn crispy and wouldn't run the motor and had to be replaced.

I'll have some time this evening to start pulling things apart .... but the strange thing is that with the dash selector set to OFF, the blower motor should not be receiving any voltage.

  My understanding of the 'flow' of electricity in this circuit would be battery - fuse - selector button - fan resistor pack - blower motor - ground.    And somewhere in that flow is ignition switch (ie., key on).    Does this sound correct?  

  And if so, why would I be blowing fuses with the key OFF?

  I'll check the blower motor connection tonight and report back tomorrow.

Update.   I checked the connection at the heater - looks good.   Checked the resistor pack - looks good.

Pulled the fuse block again to get access to the heater fan relay.  The connector to that relay was a little burnt looking, so I investigated a bit closer and found .....   the hot wire had a bare spot.   The wire had seemed to have rubbed against a metal bracket near the relay spring clip holder (the one closest to the steering wheel).

  Not sure if that's why the connector was burnt looking - but I really need to solder in some new connectors and use the Bosch relay.

Anyone have a source for these Bosch connectors and relays?    I have searched the interweb, but there the info is overwhelming.