I noticed my temp is running cool (175ish) and I thought that maybe it's the clutch fan, because it turns on as soon as I turnon the Jeep. So I bought a replacement, installed it, turned on the car, and the fan came right on.

It's about 50 degrees ambient and the car has been sitting more than 24 hours.

Should it turn on automatically like that? How can I test that the new one is working?

 

If with clutch fan you mean your viscous fan, yes that one is always 'on' and will increase in "force" when warmed up and clutch engaged. It will NOT cause your engine to run cool. In fact none of the factory installed parts would.

A fanclutch for a ZJ gives more 'roar' too so theoretically that could cool with more force.

You have any aftermarket parts installed?
Since when is it running at 175? Have you verified the temp?

 

Yep, they all spin on startup. Somebody will be along shortly to tell you how to test it. At lower temps, the fan basically just turns and is not pulling much air. When the clutch gets hot, I think the liquid in it gets thinner and flows to the outside of the fan which makes it pull more air by locking it to the pulley.

I found out that you don't store or let them lay horizontally as you will find a blob of silicone on the face of the clutch that leaked out. That is supposed to be the sign of death for the clutch. Read somewhere that you always sit them vertically to keep them in good shape.

 

Before you go crazy with the fan clutch, what degree thermostat do you have?

 

https://www.popularmechanics.com/car.../a302/1772922/

 

Sounds like you need a new thermostat, not a fan clutch.

 

did you ever test your fan clutch resistance before replacing it?