As soon as I engage the ignition key to the ON position the fan fires up and stays this way. Is this typically a relay in the fuse box stuck open or...?

bump

Open the compartment behind the fusebox and swap the fan relay with a neighboring relay with the same pin configuration. If the fan works as it should, replace the relay. If the fan keeps blowing, we'll figure out what to check next.

Sixto
87 300D

I did what you said, my relays were actually within the fuse box. I swapped the 2 closest to the fuses and it's all good now. I'll wait and see what the suspect relay does it it's new position. Thank you sixto.