Are these 5 components linked somehow?

I've got this annoying speaker noise (i can hear engine shifting in a sqeaky kind of way thru them) that happens intermittently when the wiper are on.

Additionally, at certain times, if I hit the horn, the blower motor will stop. I either have to wait and it will come on itself or I have to shut the AC off and then on again.

My indy is backed up big time and I have no clue about anything under the dash.

Any thoughts appreciated.

BTW, 300SDl, 349K miles, standard Becker radio. No alterations that I know of.

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