i have a 91 firebird w/ the L03 and has single fan setup. i replaced the thermostat with a 160 degree unit a while back and really like the temps i was running but with the stock fan not coming on until over 220, it didnt help much in traffic. so i installed a hypertech fan switch than turns on @ 176, off @ 166. after i changed the fan switch i noticed that the fan would not turn on at all. it would only turn on when the A/C is on. i have checked the fuse for the fan under the dash, made sure i had a good connection at the fan switch; all are good but still no fan. i am running out of options and patience with this. does anyone have an idea as to why the fan will not come on when it is supposed to?