electric fan won't kick on

If your 87 is like my 89, the fan is controlled and powered by the IRCM, Intermediate relay control module. Its a board with several circuits, fan, ac, fuel pump, (iirc).

Its mounted under the dash by the steering columm. Its a small rectangular black box on a metal bracket with a multi wire connector.

Ford ran full 12v power to the relay in the box and then back out to the fan.

Over time, the connectors get dirty and the high current heats the wiring an melts the connector, and sometimes the board.

The board can be removed from the box, and sometimes the box is not damaged. However the box is an important part of the connector.

Common failure and there is a Ford and several aftermarket repair wiring pigtails for the wire side of the connector.

Did this once, melted it.

So I put a high current relay under the hood to power the fan, and used the former fan power wire to simply turn the relay on an off. Its worked for 10 years or so.

The IRCMs are getting hard to find, got my last one from Rock Auto.

It its the sender, note that there are separate sending units for the gage and computer, and fan control, (iirc). Google the location to make sure you are working on the correct one.