When getting a Santana sound, you have to specify era: Early, like "Black Magic Woman?" Middle, like "Europa" live? Or later, like "Smooth."
But I can tell you how he gets his sustain, which is based on 3 elements (none of which is an effect):
1) Guitar with good natural sustain, and humbucking pickups
2) Saturated amp, like Mesa Boogie
3) Before each show, he cranks the amp up to performance volume, and finds the "sweet spot," where the notes will feedback enough to last forever, but not enough to squeal.
Hope that helps! More info here: Ultimate Santana