ok, after long last i found the answer to my own question. not sure if this is just a suburban thing or entire 1500 series platform. i found its far simpler than i expected. the 1500 5.7 series used an aux fan control system which consisted of a negative connect temp sensor to be linked with a subrelay to control the fan relay system activation. i havent found out yet what the heat range is but the part number i found is SW571 from autozone.
---------- Post added at 02:57 PM ---------- Previous post was at 02:48 PM ----------
ok fast update, autozone gave me there personal tech line. just called and its on at 208f off at 194f. a bit high for me. im running the system with a 180 thermostat. so my search continues.
---------- Post added at 03:20 PM ---------- Previous post was at 02:57 PM ----------
ok another update. i refused to accept failure in this search. i found Wells tech page listing all of there temp switches. http://www.wellsve.com/custom_searches/ds_fans.php?showall=yes
they do not sell directly to the customer but there part numbers do cross with autozone and advanced auto.