Installing a ceiling fan with led light and also a ceiling fan dimmer switch. Got all connections made fan and light no dice. There's an outlet that's connected to the same switch that works with the fan switch. From the test light I have power at all wires (except ground) at the ceiling fan box and new fan.

Here's a couple pics of the wiring at the switch. 2 sets of black white ground and 1 set of black red ground.

First thing I would do is trace out that mess and see what goes where.

Just first glance looks like the white neutral is hooked up wrong Coming out of control box it’s hooked to fan leg Most of those use red for one feed and black fir other They share neutral at switch or the fan box

How do yo have the fan wires hooked up? I know its a pain but show us or explain the fan connections.

I'd disconnect what ever is new or changed and sort the rest out with a meter, what is hot and what is not in all switch positions. Check in the switch box for what is what coming in and going out. A meter is the only only way to know for sure what each wire is doing because all the wires may have been wrong in the past.
As an example, 50 years ago the apartment house I lived had old gas light pipes used as grounds (to save snaking wires through plastered walls when the house was converted to electric) except in the dinning room there the gas pipe was hot and you'd get a jolt every time you touched the fixture. Point being the electricity doesn't know or care what color the wire insulation is and just because it worked before doesn't mean it was wired per code.

It's a huge mess. There's 3 sets of romex going into the switch box. The set with the red wire doesn't go to the fan. As far as I know it goes to the "lamp outlet". That outlet is wired with 4 sets of romex (not lying) I haven't opened other outlets.

Jbryd thanks. That's how the old switch was hooked up. I'll check it out tomorrow.

Eek.

Eek is right

I always befriended electricians, plumbers and carpenters.

You need to determine which is your line side and what wires go to the Fan/Lt.

Normally, all the whites (neutrals) get tied together in a switch box. Under a single wire nut and tucked back in the box. Not connected to the switch in any way.
The 12-2 would be your line side (power from)
The 12-3 would be your load side (power to)
The black/red wire are travelers to the fan/lt. They should be connected to the yellow/red from the switch.
Power to the switch is the single black wire. This is a common "hot" to both fan and light.
Ground to green.

That little sniffer light can show "ghosty" voltage. They aren't reliable to tell you if you have full "power". You need to test for 120v by touching a hot and a ground with a meter.

First step would be to separate all those wires and see which one is the power leg and make sure none of the white wires are carrying voltage (from being connected wrong elsewhere)

I read more of your post. Sounds like a mess. You need to shut off all power and learn how to check continuity to determine what wires go where.
Might be time to call in a professional. I've seen some awful messes from homeowners doing their own work. Scary scary stuff.

I would put money on one 12-2 being your line (power)
One 12-2 being a Line (traveler to another switch or outlet)
12-3 being power to the fan/light

Actually it's all 14g wire it looks. Doesn't matter.

Whether or not it's connected properly is another issue.

I'm wondering if you only have one hot wire going to the fan. Could you control both from that switch before, or did you have to use the pull chains?

Thanks I'll check in a while.

Old fan was pull chain worked with a "dual switch" one switch for light the other for fan. I didn't change anything.
I tried the new Lutron switch on another pull chain ceiling fan connected on the same circuit, it worked perfect.
I found in fine print can't be used with remote control fans. I just got back from home depot buying a similar fan but with pull chains.

I wish I could find a device that would give noise to locate wires.

I have been waiting on a buddy for awhile to run outlets and lights in the garage.

I wish I could afford a complete house rewire and upgraded panel. I doubt my insurance will cover that from the kitchen fire I had almost 10 months ago. They approved the kitchen rewire because that's a whole other story. Let's just say im surprised this house either hasn't burned down or hasn't fallen down.