wiring diagram for inside an attic roof fan thermostat.

To add to this, I had bought another thermostat, just in case, and this is what it looks like,

What is the likely reason 3 wires were connected together?

Mine has a less attractive and bigger metal box.

That's the shame? Really?

You don't think that all the political discussion is the actual shame?

As guilty of joining in as I am, I still think that is the real shame. To be honest, I'm surprised that nobody has blamed your wiring issue on Trump or Biden. At least not yet.

Well, my apologies, I'll admit I guessed wrong.

I think you have to admit that given your posting history it wasn't an entirely unreasonable guess.

I've certainly done similar things while having a brain fart.

And recently I very nearly did something close to that with my kitchen exhaust hood. It stopped working, when I turn it on I heard the hum you hear from a burned out motor. I saw a similar Nutone motor at the big box, and almost bought it, but decided to get the old one out first to be sure it would fit. I got the hood apart, disconnected the motor, and then - noticed a bunch of debris from the last roof job. Cleaned all that out, reconnected power, and the fan ran fine.

There's a point to this that I tried very hard to convey to my peers during 30 plus years as an engineer and mostly failed. As soon as you arrive at a diagnosis, you become blind to data that would question it. You don't reject that data, you don't actually see it at all. You need to postpone diagnosis as long as possible and look for data that would make you reject it - confirmatory data adds no information value. But that's hard.

You say that "you need to postpone diagnosis" yet you jumped at mickey right from the start, actually *accusing* him of hiding facts/data. Apologies afterwards are nice, but your initial response seems to go against the very point you say you tried to convey to your peers. Maybe you failed to convey that point because you don't actually follow your own rules? (That's a question, not a diagnosis.)

I worked with maintenance engineers who were in full agreement with delayed diagnosis, and design engineers who were mystified by it. So the lack of conveyance was really person specific. Sometimes designers are good because they're single mindedly focused on the target, but lord help us when they think they can troubleshoot.

Remember too that in Mickey's case we have huge amounts of data! hard not to inject some humor occasionally.

Political discussion is like rain; always there. Have no umbrella? Then kindly avoid it.

That's is obviously not the point, but you do you.