86 is usually a trigger
85 is usually a ground
Some relays are finicky with which terminals are excite power and ground terminals. Some it doesn't matter.
30 and 87 are your heavy power carrying blades.
If you only want the fan to run with key on when engine gets hot using the thermostat to ground circuit you are fine. You don't even need to keep the power switched as it shouldn't turn fan on unless thermostat triggers it by grounding. I still usually put those on a switch just in case. That way when the car is off, you can have the fan running until it cools to thermostat point.
