Thread: Electric fan control

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Roger nice pic

Altho I have referanced you in several posts, its because you and I and others were discussing something that you kept referring to as how you did yours instead of the issue in general--sorry if it has appearred that I was down on you---

About the turbulance and lack of flow thru the rad--

Your pic shows the a/c condensor and 4 large brackets that reduce/block flow from the front.
If you look at the pic you will see that the radiator is aprox 50% of the frontal area compared to the firewall/cowl area.
This blunt forward facing area can cause interuption of smooth flow of air front to rear of your car and the buildup of pressure in the area under the hood and behind the radiator.
Even if it doesn't completely stop flow , it will vary with speed and maybe cause overheating as the load goes up.

Do you have underdrive pulleys on the waterpump or alternator??and what is the ampereage you electric fan draw?

Originally Posted by Jerry Clayton

Do you have underdrive pulleys on the waterpump or alternator??and what is the ampereage you electric fan draw?

No underdrive pulleys, and have not measured the actual amperage draw on my fan at low/high speeds. Also have not experienced any elevated temperatures in the first 1000 miles of shakedown driving. The highest temps have been coming off the blacktop, dropping to 5-10mph for the last mile of gravel back to the house, and then not above 210F.

Originally Posted by bulldogcountry1

Looks like I just need to get an adjustable fan switch with radiator drop-in sensor. With those, don't you just turn the dial down, heat up the engine to desired running temp, then turn the dial until the fan comes on?
I also have a manual override switch, but I never have to use it.

Bulldogcountry1,
Sorry to have gotten so far off track on this thread. I believe you will be just fine with that setup. There are a lot of stand alone fan controls out there, some come with relays and some don't, and the adjustment method varies with the package but you're right on target - that's the way the SPAL package is adjusted. You'll want a relay, and like Jerry said above, switching the ground side is best, with a circuit breaker on the hot feed rather than a fuse. Other than that, you've got lots of information on sensor location, shroud holes, air flow and control theory to consider as you put your system together. Like Don said so well:

Originally Posted by Itoldyouso

That's the nice thing about this car hobby. There are so many different ways to do things and so many diverse opinions of the "right" way to do them...........but somehow the cars seem to still go down the road and function as they should.

Some electric fans can pull 30 amps on startup but then drop to between 10-15 amps.

Originally Posted by rspears

No underdrive pulleys, and have not measured the actual amperage draw on my fan at low/high speeds. Also have not experienced any elevated temperatures in the first 1000 miles of shakedown driving. The highest temps have been coming off the blacktop, dropping to 5-10mph for the last mile of gravel back to the house, and then not above 210F.


Bulldogcountry1,
Sorry to have gotten so far off track on this thread. I believe you will be just fine with that setup. There are a lot of stand alone fan controls out there, some come with relays and some don't, and the adjustment method varies with the package but you're right on target - that's the way the SPAL package is adjusted. You'll want a relay, and like Jerry said above, switching the ground side is best, with a circuit breaker on the hot feed rather than a fuse. Other than that, you've got lots of information on sensor location, shroud holes, air flow and control theory to consider as you put your system together. Like Don said so well: