Not precisely sure what you mean regards the hose changes however it doesn’t sound like anything that would cause any issues, but the first test you’ve done by bridging the connector to the fan switch should have worked, however the fan circuit in these cars is notorious for going bad and melting relays and the fuse box, so if not done already I suggest you invest in a good quality fan loom from the likes of MSD or elsewhere. You should also be able to unplug the wiring at the fans themselves (if no one has messed with it) I’d try temporarily running a couple of wires directly from the battery to see if the fans work that way, if they do then get a new fan loom ordered.