Can you explain the 3 terminals that PTC thermistors have
Okay, I figured it out. Nothing magical in that. Each terminal is just simply connected to each aluminium heat sink, and it's all down to user to decide whether to run the resistors parallel or series, or if element has more than two resistors (3 heat sinks) in whatever pattern. Just stick to the rated voltage for each resistor (formed by the insulator between the heat sinks) and you're fine. PTC is even self regulating in limiting current and heat generation at higher temperatures so no overheating should occur even if fan were of lower speed.

I'll check through these kinda small PTC heat elements and order whichever I get easiest.