radiator fan comes on as soon as I turn on the ignition

[Ed Kellock]

This just developed on Saturday.  The radiator fan comes on as soon as
I turn on the ignition and stays on until I turn it off, regardless of
temp.  It runs at the 2nd speed (1st according to Bentley).

I searched out some info on this, but didn't find an exact hit.  I did
some of the diagnostics I found and I believe I have verified that it
is not the temp sensor on the radiator.  I disconnected that and the
fan stayed on.

I also pulled both the relays for 2nd and 3rd speed and swapped them,
no difference.

The fan stops when I pull the 2nd stage relay and starts as soon as I
put either of the 2 relays back into the 2nd stage location.

I pulled the 2nd stage relay and let the car idle and the 3rd stage
does activate when it should.

The fan spins freely. and doesn't make any bad noises when it's running.

I believe the after-run function is separate, but I did find that fuse
21 was blown.  I replaced it and did not get after-run function.  I
did not get back to it after the car cooled down to test by shorting
the two after run temp sensor wires together.