Cooling fan won't shut off

New to MS3, picked up a non-runner and have been trying to work though all the issues one at a time.

Did get it running... really badly but it's running. Anyway, took it out for a short test run yesterday. Cooling fan came on while stopped at idle and it won't shut off. Finally disconnected the battery after it was parked for an hour. AC isn't on, car is completely cold. Reconnect the battery, cooling fan comes on and stays on.

Bad temp sensor somewhere or is there a relay that could be stuck closed?