2008 F150 4.6L Electric Cooling Fan runs all the time - even with AC OFF. If I disconnect the fan clutch electrical connector, the fan runs several more minutes before "freewheeling".

Can you clarify, please? Are you saying when you remove the electrical connection from the fan, it somehow is still receiving electrical power, and operating?

At any rate, if the clutch on the electronic fan stays engaged when the electrical connection is disconnect, I suspect there is a mechanical malfunction with the clutch itself (within the fan mechanism). I know of no serviceable parts to the unit, other than replacing the entire electronic clutch mechanism. Motorcraft brand will set you back about two hundred bucks. Off brands, maybe 120 bucks or so.

I appreciate your taking time to answer my question. If I disconnect the electrical connector for the clutch fan, it takes a few minutes, but it does disengage. If the connector is connected, the fan runs all the time. To make sure I am clear, it is a mechanical fan, but uses an electric (PCM controlled) fan clutch. So, it might be: PCM glitch, or sending unit failure, or mechanical clutch "sticking".

You will have to do a little research for your particular make and model vehicle to see when and how the clutch is engaged. I would suspect switching is determined by the temp control sensor usually mounted somewhere around the thermostat housing or manifold. Normally the fan does not come on when the engine is cold, like the first thing in the morning. This facilitates the engine coming up to operating temperature, which is critical in today's engines. If you locate the temp control sensor, try unplugging it first thing in the morning and see if the fan clutch engages. If it does, then the problem is not there. If it fails to engaged with the sensor disconnected, the sensor may be faulty.