electric fan won't kick on

[87LXVERT]

87 2.3
electric fan won't kick on no matter how hot the temp goes. it will overheat sitting idling. I've tried two sending units. If I ground the wire the fan kicks on. Two bad units or wrong ones? one from rockauto and the other from ebay i believe.

 

[Rcdgl]

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.

 

[87LXVERT]

Thank you for your reply. I must be on the right sending unit because if I take the wire off and ground it the fan comes on. The sending unit is just an on/off grounding switch. Just hard to believe two units don’t work.

 

[WORTH]

Thank you for your reply. I must be on the right sending unit because if I take the wire off and ground it the fan comes on. The sending unit is just an on/off grounding switch. Just hard to believe two units don’t work.

It may be 2 bad units, after all quality control is a thing of the past. However it just may be the engine is not hot where the fan switch is, or it is losing pressure and can't get to 220 degrees to trip the switch before it boils over. Could be as simple as a bad rad cap or a pinhole leak someplace. Water will boil at 212 if it isn't under pressure. Pressure test the cooling system, and the cap.

 

[87LXVERT]

You may be on to something. I know for sure I have a pinhole in my heater core. Takes a long time to lose any substantial amount of coolant but see the puff of steam from vents if I turn on the blower. But also I see the temp gauge go high enough that it should trigger the fan. When I overheat the needle is pegged. I'll bypass the heater core and see what happens. I don't drive the car in the winter but nice on a cool summer night to have the heat going or defog the windshield.