Hello everyone, longtime lurker here and I hope this is in the right topic place. My recently acquired Benz has an issue I’ve never dealt with nor could find any information on. The blower motor only works with the key in the run position, but shuts down once the car starts. I replaced the speed switch, the current climate controller is a rebuilt unit from the previous owner. I plan on pulling everything out to chase a potential break in the wiring this weekend. Also my blower motor screams like a banshee, plans on replacing that is in the works. Anyone deal with this before, or know of this issue? I’ve owned a couple 201’s and usually get the ticking or sporadic on/off. The cold is coming and I need a defroster!

TL;DR blower works on start position, but shuts off when engine runs. Any advice is appreciated! ~275k miles

Additional tidbits: 2.5 NA, automatic, replaced lifters, chain tensioner, master cylinder, fuel lines and filter, oil change and filter and interior swap from my wrecked 84 2.2 (may it rest in pieces)