I have a 1991 5.2L in which the cab air blower slowly got more intermittent and finally stopped altogether. With the key on the other accessories work, but there is no power at the HVAC selector and no power at the resustor plug. There is full 12V to the 50A fuse in the engine compartment, but only about 1V across the fuse poles, so the wire may be hanging on by a thread somewhere I guess. Since the fuse is getting 12V when referenced to ground, I know that the problem is after the fuse. I tried hot wiring the blower fan directly and it spun fine.

Any ideas on this one? I thought maybe a fusible link, but I don't know where it would be and my Haynes manual is still in the mail.