What is the best way to run wires from my battery to inside the cabin to wire in a power converter?

main ignition fuse is only for just that...

if you checked that the circuit to that power outlet is OK, including the wiring, maybe the jack itself is bad

disconnect it, then use jumper wires to the battery to see if it powers on

If that is true..It may be above just under the dash.. Some wiring connects directly to the fuse block inside the vehicle. I you are thinking about running a hot wire directly from the battery and you drill a hole make sure there are no components in the way , you put a rubber grommet in the hole and seal it once the wire it run through.. And be certain to fuse the wire. Check online for wiring schematics and you may not have to drill a hole. Also some vehicles PCM;s are affected by additional circuits ..check with the dealership.

alternator or associated wiring suspect... test for 14.4 volts at battery when all is hooked up proper and running.. if less replace alternator or diagnose further the wiring to and from alternator

A wiring problem or the driver's master switch, probably. Check for broken wires in the harness going into the driver's door opening. A dark green wire is the power wire to the switch (from a 30 amp circuit breaker in the relay block). and a black ground wire from the switch going back into the cabin.
Pull the master switch out and check for power on the dark green wire at the connector, with key on. If no power, wire may be broke from the circuit breaker to the switch, probably in the door opening. If power is good, check the ground circuit from the switch connector to ground. Like this: voltmeter positive lead on the green wire terminal with key on, voltmeter negative lead on the black wire terminal. If voltmeter registers battery voltage, power and ground is good. If no voltage shows on voltmeter, power or ground is bad. Move voltmeter negative lead to a good ground on frame or body. If voltage shows, power is good and ground is lost-look for broken black wire in door opening. Check for the black ground just inside the cabin from door-maybe under the driver's kick panel.
If both power and ground is good to the master switch, try a new or used master switch.

Might have broken wiring harness wires that run from the cabin to the door. There is a rubber boot that covers this harness, runs near the door hinges, remove boot and check all wires and if you find any damaged or broken, repair and test auto door lock.

cannect it to the battery via the fuse block either inside the cabin or the one in the engine compartment. To get it inside the cabin you would have to go through the firewall. Either drilling a hole using a grommet running the wire then sealing it, or, run the wire with something else that goes through the firewall into the cabin.

The simplest way would be to run a wire from the positive battery post to your toggle switch. Make sure you put a fuse in it. Then run from the toggle switch back out to the fan. Unplug the factory wiring and plug you wire onto the power feed terminal at the fans. To find that, just use a jumper wire from the battery to each prong on the fan until it turns on. Plug your toggle switch to that prong. Hope this helps.

Try looking to where your bundled wire harness, almost looks like a huge power cable goes from the engine compartment into the firewall.

To run any wire through the firewall, find a spot that is both reachable and unobstructed on both sides of the wall. I generally use a very short bit so after penetrating, it does not accidentally plunge into other wiring or components, or I use a collar over the bit (a small piece of tubing, leaving only 1/4" of bit exposed) I sometimes also "cheat" by poking a hole in the rubber boot where the steering column goes through.
Whenever passing a wire through sheet metal you must install a grommet. (if none are available, you can make one by using a piece of rubber tubing or the cut off end of an old tire valve.)
When tapping power from the battery, you will need to use a relay and switch attached to the "accessory on" side of the ignition switch, to prevent whatever you are installing from remaining on after the vehicle has been turned off. Use fuses in all new power sources as well to protect the vehicle and your new install from damage.
In creating a new circuit, you have the opportunity to use shielded wire, which will prevent stray electrical "noise" in your set" not a bad idea to do that.
good luck

A\C control module located in the heater box under the hood two plugs single red wire on the passengerside purple wire and two black one has a stripe i think $90 (autozone) to $185 napa my best guess