I assume your Jeep did not come with an electric fan and the temperature sensor you have is for the gauge. With some electronics, that sensor could be used to turn on the fan but probably wouldn’t be worth the cost.
The problem with the fan is we don’t know what the connections do. One could be the armature and one could be the field but doubtful. I would expect the fan to be series wound, armature in series with the fields. There could be two sets of fields. There could be just a resistor between the different leads to provide the low speed.
Without knowing more about the fan, we don’t know if we can connect both leads at the same time of if we need to only connect one at a time. For automatic operation, that would require that the relay that energizes the high speed to de-energize the low speed and vice versa.
Do you know what year Grand Cherokee the fan came from? Do you have the pigtail (plug with some leads on it). I did a search on Grand Cherokee fan and found one with 3 wires that was controlled by the ECU. I could read that the black was ground but it was just a small, almost thumbnail size, picture and when I clicked on it, I got “File not found”.
Personally, I wouldn’t touch the Summit kit without knowing what parts it uses. We can use parts you can readily get replacements for at about any auto supply or salvage yard.
Thanks....and hopefully this doesn't start another slaggin war
At least it’s kept your thread near the top where you can find it easily.