1987 300SDL Aux. Fan Troubles

[british_atlantic]

Greetings.

My aux fan refuses to cooperate.

About a month ago the fan on the car blew a fuse and turned out to be locked up. I swapped the fan with one from my 420SEL parts car and had no issues. Nothing notable happened since, but this week it that decided it'd rather not function.

I have been reading around and have done some fiddling.
1. bench tested the fan and it does function off the battery
2. jumped the 2 wires to the ac condenser with a fuse to no avail
3. checked the fuse and swapped with the one for the door locks
4. put my test light in both ports on the plug for the fan, not hot

I haven't put any effort into investigating the high-speed switch, cause obviously that shouldn't be needed in current operation. It still doesn't come on in excess of 105c though. I imagine that the low speed switch in the AC system is also not the problem as bypassing it doesn't make a difference. My next thought is investigating the relays. I have found discussions talking about jumping wires in the relay ports however the instructions are based on the wiring diagram that I do not have. Perhaps the fan is no good but again, it works straight off the battery.

I guess my ask is if anyone can think of anything that I've not done or if anyone has a wiring diagram file/link. Thanks!