No power from HVAC resistor?

Your diagram does show different wire colors, but it's for a different model too. Don't know how similar they are in other respects.

Once we have this solved, remind me to share the ordeal a co-worker went through on a Caravan rear wiper problem.

Regardless of color, look again at the connector view for the ignition switch. There's three terminals in one row and four in the other. Terminal ""G" is at one end of that row of four, and terminal "F" is right next to it. Jump those two together with a piece of wire or a stretched-out paper clip. I bet the fan motor runs. Be aware the paper clip is likely to get hot.

If you check on terminal "F", you're going to find 12 volts all the time. I know that because that circuit feeds two other parts of the ignition switch, one being the starter relay, and that works. The 12 volts is not showing up on terminal "G". There's only the internal contacts inside the switch, and the connector terminal for "G" that can be causing the missing 12 volts.

If jumping "G" to "F" makes the fan motor run, and you don't see any signs of overheating in the connector terminal, pop a new switch in.

If you do see signs of melted connector body or blackened terminals, the repair is more involved. There's no way to know which came first. Overheated switch contacts will generate heat that migrates out and degrades the connector terminals. Overheated connector terminals will generate heat that migrates in and degrades the switch contacts. Once that starts, it snow-balls until both parts must be replaced. If either overheated part is not replaced, it will continue to cause the same damage and a repeat failure.

Most of the time the connector body is too badly melted to allow the terminal to be replaced. Rather than replacing the entire connector, what I do is cut out the black terminal and cut away the melted part of the connector body. Most of the time this happens to both wires, in this case terminals "G" and "F". Both of them will have the first four inches of their wires hardened from the heat. Solder won't adhere to that, so cut those four inches off. Splice on four inches of new wire of the same gauge. Solder those splices, then seal them with heat-shrink tubing. Never use electrical tape as that will unravel into a gooey mess on a hot day.
Install a pair of crimp-style terminals but solder them too for the best connection.

Replace the switch, plug in what's left of the connector, then plug in the two wires with their new terminals individually. I like to squeeze them a little with a pair of pliers, so they make a solid connection.

Fingers crossed.

So, a coworker was tasked with repairing an early '90s Caravan with a dead rear wiper. He started at the switch on the dash. Tried a new one, no change, still not working. Next, he assumed there was a problem in the fuse box. The fuse was good, but I pointed out that same fuse is one of two that power the Air Bag Computer. They did that because if the rear wiper fuse was to blow, you'd never know it until you needed that wiper. By tying it to one of the two Air Bag fuses, if one blew, the other one would provide the power to turn on the "Air Bag" warning light. That's the clue that tells you something is wrong, and you have it repaired before the dead rear wiper becomes a safety issue.

Next, he found a yellow wire that was supposed to power the rear motor. Turned the switch on and had no 12 volts coming out of it. Pulled that wire out of the connector, now there's 12 volts on the switch terminal. The clue here should have been there's some random voltage with a digital voltmeter, but it won't power a test light. He was finding some stray or random voltage from the rest of the interconnected circuitry inside the switch. This wasn't really a power wire.

Assuming that wire was the cause of the problem, he checked it for being shorted to ground. He thought it was. The problem now is how to find where that wire is grounded.
To boil down the next two days of frustration, he had the service bay next to the van filled up with the driver's seat, the middle seats, the rear seats, the carpet, both side trim panels, the lift gate trim panel, and spare tire. The head liner was removed and the dash was pulled back about a foot. It looked like the van had exploded. Somewhere about this time I was talking with the people in the parts department while they looked up parts for me, and I happened to mention, "is he aware there's a small module in the lift gate for just the rear wiper"? One of them found a new one, and ran out to give it to him to try. Ten minutes later the wiper was working. Problem solved.

Now, to put everything back together, it would have been faster to load up all the parts, take them back to the factory, and have them run it down the assembly line again. Instead, he spent another day doing that.

This was a lease return so the dealership was paying for the repair. Luckily no customer got saddled with the bill. In cases like that, I'm happy to say the service department often stopped totaling up the time. They still paid the mechanics, but stopped charging the customer. I was involved with one like that where the customer had to come back nine times before I figured out the cause of his interior lights turning on intermittently. That's a story for another day, but all the way through, the customer was very understanding and appreciative. I finally fixed what at least one other person could not.

Happy to hear you solved your fan problem. The mouse is an option that's only supposed to be used in applications where the fan wheel is mounted vertically. That way, when you turn on the switch, it tickles him in the butt, and he starts running. When the fan is mounted horizontally, a minimum of centrifugal force is required to keep him up on the wheel, so the engineers are limited in how slow the slower speeds can be. He can give 'er holy smoke on the higher speeds, but once the bearings in the motor get tight, it slows down too much and he falls off, then you have a dead fan.