COOLING FAN SWITCH - 85-86 Thunderbird or Cougar
by Jim Portteus

If your Radiator Cooling Fan isn't working on your 85-86 Thunderbird or Cougar, here's a way to wire in a manual switch to control the fan. 

First, insure that your Cooling Fan does work.  You can do this by using a 12-volt hot wire and a ground wire.  Unplug the fan and connect the wires to the terminals on the fan plug.  Be sure to keep clear of the fan blades!

Tools you'll need:      Torx Bit Screwdriver

                               Phillips Screwdriver

                               Wire Cutters/Crimping Tool

                               Light (Circuit) Tester

Parts you'll need:      15 amp 12volt Lighted Rocker Switch

                               30 amp Relay

                               25 amp Fuse and Fuse Holder

                               7   12 gauge (Blue) Spade Connectors (for the back of the Switch and Relay)

                               1   10 gauge (Yellow) Butt Connector (for splicing)

                               2   12 gauge (Blue) Ring Connector (for ground wires)

                               ~24 inches of 12 gauge wire

If your fan motor is OK, locate the Fan Control Relay behind the glove box.  You access it from under the glove box.  It's held on with one screw.  You may have to take out the glove box, but on mine there was enough slack in the wiring to pull the whole unit down.

You'll need to leave the box in place with all the other wiring because this relay also controls the A/C Clutch.

                                       Fan Control Relay

This is how the wiring is on my car:

     Fan Control Relay Plug

Wire/Stripe Color  Gauge:       

1.    Yellow/Red              16      From Coolant Temp Sensor in Lower Intake

2.    Orange/Black           12      Always Hot

3.    Orange/Blue             16     

4.    Black                      14      Ground

5.    Brown/Yellow          12      To Radiator Fan

6.    Pink/Blue                 14      From Heater/AC Control (signals A/C on)

7.    Black/Yellow           16      To A/C Clutch

8.    Grey/Yellow            12      Ignition Hot

Tap into the #8 wire and connect it to the 12V+ terminal on the switch.  I just cut the wire in two, and stuck a new 12 gauge wire along with one end of the #8 wire in and crimped, then stuck the other end of the #8 in the other side and crimped it.  You could use one of those blue wire tap things, but I wouldn't recommend it.

Now connect the Switched terminal (sometimes labeled "Acc.") on the switch to Terminal 85 on the Relay.

Connect a wire between Terminal 86 of the Relay and ground.

Splice into the #2 wire to feed 12V to the Fuse Holder w/ fuse.  Then connect the other end of the fuse holder to Terminal 30 on the Relay.

Cut wire #5 and connect it to Terminal 87 on the Relay.

Finally, connect a short wire to the Ground terminal on the switch (be sure to ground the other end of this wire).  This wire lets the switch light up so you know the Fan is getting power.

Now mount the switch using one of the screws that holds the glove box. 

I've found that I don't have to run the fan when it's cool outside (unless I let the car sit and idle for more than a few minutes).  You will want to run the fan whenever you run the A/C in the summer, though.  This will keep air flowing over the A/C Condenser (in front of the Radiator) so cool air will keep flowing inside your car!

A side note:

I now have installed a Thermostatic Fan Controller (Carquest part number 77528).  It can control two fans (with the addition of another fuse holder) and also ties into the A/C so the fans run whenever the A/C is activated.  This provides me peace of mind that the car won't overheat if case I would forget to turn on the fan manually.  The install took me about 2 hours.