Is what this guy saying correct? I thought Lt1 fans turned on at a certian temp and had a temp sending unit.

"Fans are fans man... they accept incoming 12v power and push air. There is no special temp sensor inside the fan unit, especially for LT1.

All of your electronics are outside the fans and then you relay the power to them at the right time."

If you're talking about LT1 as in 90's camaro's birds and vette's, that's basically true.

My 93 vette has 2 fans. Wired to 2 relays located on the side of the radiator box. The engine computer controls both of the fans, one on at 220, the second at 235, and both all the time if the AC is on. All of this can be changed with a tuner.

he is correct- there is no sending unit inside the fans.
they are either turned on by the ecm, or by a thermal switch that grounds the relay at a certain temp or when the AC is running.

If you're talking about LT1 as in 90's camaro's birds and vette's, that's basically true.

My 93 vette has 2 fans. Wired to 2 relays located on the side of the radiator box. The engine computer controls both of the fans, one on at 220, the second at 235, and both all the time if the AC is on. All of this can be changed with a tuner.
Yep, this is how my Impala is as well.

I ran this setup on my old 68 radiator until I recently swapped in a be cool system. Those fans pull alot of air!