Well, my 1994 Grand Cherokee has hit 200000 miles and it's about time to do something about it's cooling system.
It overheated on the freeway some weeks back and I about killed it driving to an off ramp (with it bucking and rattling all the way). I'm sure I hurt it some, but once it cooled down, I was able to put some water in it and drive it home. The head gaskets seem to have held and I can't tell much difference in how it runs, maybe there's a lope at idle. We bought it used and have put some hard miles on it. It has some idiosyncrasies. On the test drive, before we bought, it wouldn't start. They pushed it into the shop and I watched from a distance as they fiddled with the battery and got it started. I guessed that one of the cables wasn't tight, but later found they had added a 16 ga. wire from the battery negative post to the chassis. Pull that wire off and it won't start to this day (I have swapped out that wire for something heavier). The other thing was the cooling system was always marginal, prone to hissing and bubbling when you shut it down. It's continued to do that over the years despite getting a new radiator and water pump. Still, I like the durn beast quite a bit.
As I didn't kill it, I decided to go full Monte on the the cooling system. Flush, new radiator, new thermostat, new water pump, and a new fan clutch. I was feeling pretty good when finished with that, but it still wasn't up to speed. I did read on some forums that folks had swapped in early 90's, Ford Taurus, two speed, electric fans with excellent results. There were also quite a few different ways to do this. Some used Volvo relays and BMW sensors, others used relays and switches, and there were those with solid state controllers. I decided to go whole hog using a controller.
Here's the fan in place:

It's mounted upside down from what it would be in the Ford. I made some brackets to hang it and sheet metal covers to close up some open areas on the shroud.

I mounted the two relays needed for fan power to a bracket I made from a defunct lawn chair:


Here's the sensor I used:

It's mounted in a heater hose. The adapter I used did not have place to mount a ground for the sensor so I welded a small tab to it.

I lucked out finding a hole through the firewall for the controller wires, as this year still had holes to mount a clutch. There was a cover plate but that came off without issue.


Grounded:


Fused power:


Continued...