Heater blower does not blow air

Six cylinder front wheel drive automatic 250,000 miles.

I bought the car cheap. I knew it had a couple issues. These may or may not be related, so I will relate them all.

Now: for about two weeks, the heater blower would work when it wanted to; the speed control setting made no difference, I could change the setting when it was working, I just could not get it to work if it did not want to. Occasionally, after a couple miles of driving, it would come on on its own. If it did come on, it would stay on until I shut the car off.

It would occasionally speed up and slow down (flutter) on its own, and I felt that it would be shutting off soon.

Then about a week ago, while it was blowing and I was driving, it went off and has stayed off ever since.

On the advice of a couple "well-meaning, semi-knowledgeable" friends and coworkers, I have done the following:

1. Removed and bench-tested the blower motor - it works.
2. Replaced the blower motor speed control switch.
3. Replaced the blower motor relay.

None of these has fixed the problem.

I have also checked every fuse in the block that has any sort of "AC" label. They are all fine.

Possibly of note: The car sat unused for about four months immediately before I bought it, mice in the wiring? I do not know. I am lost and lousy at wiring.

Any ideas?
Thank you in advance.