electric fans
7t3 In 10ec
7t3 In 10ec
Use this diagram, and this T-stat. Basically you are powering the relay from the alternator. You are triggering the relay with a switched IGN source like the yellow wiper motor wire, or the ACC slot in your fuse panel. The power from the relay goes to the fan power wire, and you ground the fan to the frame or engine.
Now, the relay needs a ground, and this is where the T-stat switch comes in. Mount this switch in the passenger side head, opposite where the temp sending unit is on the driver's side. It is a temp switch, that uses the engine as a ground. When the temp is low, there is no connection so the switch has no ground. When the temp is high, the switch connects to the ground through the block giving the relay a ground so the fan turns on.
T-stat switch:
http://store.summitracing.com/partde...5&autoview=sku
Diagram:
Now, the relay needs a ground, and this is where the T-stat switch comes in. Mount this switch in the passenger side head, opposite where the temp sending unit is on the driver's side. It is a temp switch, that uses the engine as a ground. When the temp is low, there is no connection so the switch has no ground. When the temp is high, the switch connects to the ground through the block giving the relay a ground so the fan turns on.
T-stat switch:
http://store.summitracing.com/partde...5&autoview=sku
Diagram:

DON'T I NEED TO UPGRADE TO A LARGER ALTERNATOR FIRST?
It's a good idea but there are guys with electric fans and a stock alt.
Here, this may help you with the alternator upgrade. It's not expensive, and relatively easy.
http://photos.imageevent.com/durango...%20Install.pdf
Today I went and got a "modern" switch that I put into the thermostat housing in place of the vacuum thermo switch (I've removed my AIRS system) so it was a perfect place. If you can't use that, OReilleys has a thermostat housing with 2 threaded holes, the second can be used for the fan switch.
Hope this helps.
7t3 In 10ec
The following was made for a '66, but the core height is the same for yours so it will work just as well.
Materials:
Get two 22" long 2"x2"x 1/8" aluminum angle pieces.
8 - #6x3/8" machine screws with flat (not pan) heads
2 - #6x1/2" machine screws with flat heads.
10 - 6" nuts & washers.
Automotive weatherstripping. I used a combination of 1/4" thick x 3/4 wide and 3/8" thick and 3/4" wide. 1/2" wide would have worked better, but the hardware store was out.
3/16" drill bit
masking tape
12 or so Aluminum pop rivets.
Place angles on radiator making sure they are snug against the hat. Drill five holes ~ 5/32 along top and bottom of plasic shroud - see photo below. Place drilled shroud on angles and mark the holes on the angles. Remove angles and drill holes corresponding to the shroud. Flip them over and carefully countersink the holes so the heads of the screws are not protruding above the aluminum. Be careful and don't go too deep or you will open up the hole and the screw will pull through.
Bolt up the angles and shroud by hand for a test fit. If ok, mark the angles inside the fan area for trimming.
I used a jigsaw with metal cutting blade to remove the marked area per above. Reassemble the angles and shroud for a final test fit. If ok, place weatherstripping along sides of shroud to seal any air leaks and to get the angle brackets 1/2" or so off of the core. It will look something like this when you are done.
To attach the angles to the radiator take the 3/16 bit and wrap the masking tape around he bit ~1/4 from the tip about 1/8" thick. This will act as a stop and prevent you from inadvertently drilling into the core when the bit breaks through. Mark six evenly spaced holes along the top/bottom of the brackets. Using a clamp(s) (soft jaws/scrap of wood between clamp and rad.) compress the shroud assembly 1/8 inch or so to help seal and hold weatherstripping in place against radiator. CAREFULLY drill the marked holes and rivet the radiator and shroud assembly together. It will look about like this when you are done (It isn't riveted yet in this image):
Good Luck,
-Lurkin
Last edited by Ben Lurkin; Feb 28, 2008 at 12:32 AM.
Now, the relay needs a ground, and this is where the T-stat switch comes in. Mount this switch in the passenger side head, opposite where the temp sending unit is on the driver's side. It is a temp switch, that uses the engine as a ground. When the temp is low, there is no connection so the switch has no ground. When the temp is high, the switch connects to the ground through the block giving the relay a ground so the fan turns on.
T-stat switch:
http://store.summitracing.com/partde...5&autoview=sku
Diagram:

The Best of Corvette for Corvette Enthusiasts

Why wouldn't the BAT terminal on the alt be 12V constant? It's always hot even when the engine is off.
What year was the Focus?
looks like an awesome setup. I just bought the March Performance underdrive system and need to do the electric fan thing. As usual, you seem to have come up with a very sensible plan.
Cheers
Bill
I guess it pays to stop in every now and again. I had no idea. I spend the summer in the vette and the winter on here

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