First off, thanks for the info on the infamous Blower Motor Resistor a.k.a.
Blower Control Module found on this site.
My initial problem was that I was getting heat to seep out of the vents but the fan was not blowing. My LSS is equipped with the Automatic Climate Control complete with passenger zone. Test-trying a new fan did not solve the problem, and later the existing fan did come on at mid speed only once so I knew the fan could
work. From my research here especially, I determined the problem was most likely the Blower Motor Resistor.
I took me a full hour to get to the existing unit and pull it, but in the meantime I learned a lot about the electrical firewall components. One thing I found is that I had to slide out the driver'* side fuse block (and therefore pull the linking grounding screw between them) to get to the 'hidden' nut behind the wiring bundle on that side, which in turn killed the clock and radio memory. Poor design in my book but oh well. I then pulled the whole fuse panel assembly forward to get to the Blower C.M.
A trip to a local junkyard yielded a replacement from a '96 Buick, however, a quick test proved it was bad unit as well - when I hooked it up to the connectors- it immediately kicked the blower on high without the key in the ignition--the most notorious failure of these parts. Later, I totally scored when I turned in the bad unit for a much-needed lower valence and splash shield from a '98  Regency.
So I went to eBay purchased a unit out of a '96 Bonne SSE. I Just put it in and voila! I've got working heat again!!
BTW, most new blower motor resistors for the ACC cars are listed at $180 from most sources. I found the best price for a new one at O'Reilly'*/Kragens/Checkers for $120-ish. The used unit I got from eBay was $44.50 shipped. The JY one that was no good cost $16 at a pull it yourself lot. I could have kept playing Russian roulette to find a good one, but I figured the time saved because the eBay seller attested to it being good was worth the extra $30 spent. The OEM AC Delco Part No. installed was PN 16173860. The aftermarket replacement PN is RU1004, which looks different from the OEM, but is supposed to be a superior design. Another tip I'd like to pass on, test out the components by just making the electrical connections before completely installing-- it definitely saved me a lot of time and frustration.