1. Remove the Mechanical fan and mounting hardware:

   Remove the top fan shroud. There are bolts along the top of the 
   radiator and down along the side that connect it to the lower half 
   of the shroud. 

   Remove the 4 nuts that hold the fan blade on and remove the fan and pulley. 

   From the underside of the car, remove the 2 bolts that hold the lower 
   half of the shroud on, and remove the shroud. 

   The bracket that holds the idler on is held on by three of the water 
   pump bolts.  They will need to be removed along with the bracket. 
   Replace the bolts with shorter 3/8x16x4 bolts.  They can be bought at 
   any hardware store. Use thread sealer on the threads. 

   Replace the upper fan cover with one from an Impala or Caprice with 
   dual electric fans. GM part # 10281082 $9.09. All prices for parts are 
   prices I got from GM parts direct. 

   Install the electric fan unit. It is held on by a slot on the bottom 
   and a screw on the top and side. I found it easier to remove the screws 
   on the other fan to match them up for size. There is a long one on top 
   and a short one on the side.
 
   If you are buying a new fan they come in three pieces.  
   The motor,     part # 22137318 $47.25.
   The fan Kit,   part # 12365300 $48.50.
   The motor kit, part # 22135365 $57.50 

   You will also want to remove the crankshaft fan pulley. Just 3 bolts. 

2. Wiring: 

   Start by disconnecting the battery. Then remove the power supply "large 
   cable" from the underhood fuse box. Disconnect the plug in connector on 
   the back side of the box. This is done only to make it easier to work on. 
   Remove the bolts that hold the box in place. The box is actually a box 
   within a box. To separate them find the retaining clips that are located 
   between the walls of the box and remove the outer shell. Now you can get 
   to the wires on the back of the fuse box. Using the diagram on the lid of 
   the fuse box, locate the empty 40 amp fuse position for the primary fan. 
   Using 10 gauge wire and a female spade connection, insert from the bottom 
   of the fuse box, the connector into the unused side of the fuse connection. 
   You may need to enlarge the slot a little to insert the connector. The other 
   side is switched power. Install a 40 amp Maxie fuse. Run enough wire to go 
   where your relay is going to be mounted. The fender well is a good location. 

   Now using the diagram on the lid of the under hood fuse box, locate the 10 
   amp fuse labeled primary fan. Connect a 14 gauge wire to the fused side, to 
   the location where the relay will be mounted. 

   Reassemble the two parts of the fuse box, neatly route the wires. Reconnect 
   the power supply cable to the under hood fuse box, and reconnect the plug on 
   the back. 

3. Wire the PCM: 

   Connect PCM pin, Part # 12084913, $1.11 to a roll of 20 gauge wire. Remove 
   the Red 32 pin connector from the PCM. Open the plastic cover over the wires. 
   There are 3 little plastic tabs that allow you to do that. Insert, "Push" the 
   pin into position # 11. They are numbered on the connector. That is the ground 
   signal from the PCM to turn on the relay. You can see that the pin goes all the 
   way in as it is made of clear plastic. Reinstall the connector on the PCM. Route 
   the wire to the location of the relay. 

4. Wiring the relay: 

   Mount a 30 amp relay to your fender well. Four position relays are labeled by 
   numbers.  Numbers 30-85-86-87. 
   At # 30 you will connect the 10 gauge wire that you have coming from the 40 amp 
   fuse from the under hood fuse box.              
   At 85 you will connect the 14 gauge wire you have coming from the 10 amp fused 
   position in the underhood fuse box. 
   At # 86 you will connect the 20 gauge wire from the PCM. 
   At # 87 you will run a 10 gauge wire to the positive side of the fan motor. 
   From the negative side of the fan motor you will need to run a 10 gauge wire to 
   a good ground. There is a ground just in front of the battery that is easy to reach. 
   If you can find a plug connector for the fan, perhaps at a junk yard, it will look 
   much nicer. If not you can use insolated spade connectors.