ECM replacement?

Check that EMIS 2 15amp fuse as well. Make sure it looks okay, has no signs of heat which would indicate resistance in that area. That fuse feeds the fan relays as well.

Then yes on pin 86, if you're reading 3v, that's voltage drop on the ground circuit to the ECM, or one of the ECM grounds is corroded. The ECM grounds are going to the top right of the engine block. But if you can follow the dark green/white wire from the fuse block and see if you find any contact points where it might have rubbed threw and got corroded inside. But that ECM is in the left front of the engine compartment. Probably under the fuse block. It's got 2 bulk connectors going to it.

That's odd about the pins being backwards. I'm going to check if it's different on another model. But these diagrams are from All Data. It says pin 30 comes from A/C clutch fuse and 87 goes to compressor.

Yes, facing the engine, left front is ECM.

Here's the instructions for pulling the top off. They can be tricky.

If you can pull the box up enough just to see underneath, maybe try a mirror. You just need to inspect the connections. Check any engine and body grounds as well. They need to be clean and tight. Here's a technical service bulletin that might help.

Can you just unbolt the whole box? All you need is look underneath. You don't really need to pull the whole box apart. You should be able to see underneath by unbolting it from the body. In the picture also, there's your ECM.

Does this vehicle have a battery in the back as well?

There's a bulk connector in back near the battery too. It's behind the trunk inside panel incase you need to check back there too. And yes that's a good service bulletin for this issue.