LanceD

what temp does it come on, and can you tell when it comes on? I was offroading the other day, and temps got pretty hot and I don't think it came on, how can I check it?

clutch1

Grab it!!!!!! Nah just kidding. You should be able to hear it when it comes on.
Mine doesn't come on a preset temp. all it is silicone. If you think it is not coming on at all just get out, with truck off and grab the fan and turn should spin free. Most of the time these things lose all the silicone and stay engaged all the time. Mine works good but when i'm pulling the temps start going up and if i let off then i can hear the fan come on. I always keep an extra clutch that i got at the junk yard in the truck, turned it upside down to let the silicone run out and lock the clutch in, just in case

clutch1

Sorry, shouldn't spin free if hot, if cold it will.

gmctd

Turn it when engine is cold, noting the resistance to spin - the silicone is cold and thick, and gravity causes the fluid to settle to the lower half of the clutch diameter.

Turn it when engine is at operating temperature, noting that it spins somewhat freely - the warm silicone is thin, and centrifugal force has "stored" it in the reservoir channels

If radiator temp is hot enough to require more fan, the clutch will have similar resistance as when cold.

You will need to shut engine down and try it immediately, because the clutch engages based on air temperature thru the radiator, and the thermo-coil has 'gated' the silicone into the hydraulic coupling channels

Leave it sit a few mins, gravity drains the silicone back into the reservoir channels, and it will spin freer than when checked immediately after shutdown.