1989 Trooper R/S
There all all kinds of electric fans. Some are dual fans, others are two speed singlefans, and others are single speed single fans. Most are set up with a fan switch in the coolant circuit so they will only come on when either the A/C is on or the temp in the coolant system is higher than the setting of the temp sensor. I have an 89 that came from the factory without air and it came with the large plastic fan, a shroud and a fan clutch. One thing to check is to make sure you have at the least a 2 row radiator. I do know some of the early Troopers without air came with a single row radiator and a small 4 bladed fan. My temp never goes above half and I'm in Texas where it's over 100 lots of the summer days. If you install an engine drivin fan I would get the large fan, a shroud and fan clutch, and make sure your radiator is at least a 2 row.
There all all kinds of electric fans. Some are dual fans, others are two speed single