If it were me, I would use a "fuse buddy"
http://www.centurytool.net/305...y_Mini_p/esi305m.htm
to see how the load across was acting.
given it blows while driven, I would suspect the circuit is being overload when the fan comes on. BUT, it might be the circuit has an unwanted high load prior.
the original fuse 12 originally provided the old alternator warning light so that would be on my high probable list as a source of unwanted current draw
Fuse 13 and 14 (power windows) loosing power when 12 blows is an egnima! I didn't find a schematic on pantera electronics sight to see how the key power buss was arranged
PANTERA INTERNATIONAL
A DE TOMASO CAR CLUB
Presents the De Tomaso Forums
The On-Line Meeting Place for De Tomaso Owners and Enthusiasts From Around the World
Clicking on the banner will take you to the sponsor's website.