Should the fan on my sec be harder to turn (engine off) when the engine is cool or warm? I just fitted a brand new fan clutch and it has very little resistance when the engine is at operating temp, much less than when its cold.

Sounds like the proper operation.

Viscous fan should be able to turn with little resistance when the engine is cold, but as the engine heats up the fan coupling should gradually lock up and at 85c engine temp there should be a fairly high resistance to turning by hand.
Geo.

My newly purchased unit must be faulty then, thanks for the reply's. I just wanted to make sure before I went and made a fool of myself at the parts store.