For those with aftermarket electric cooling fans
 

The unit I have uses a temperature probe that pushes into the radiator fins to sense when to come on. I have never liked the temperature that the unit was turning on at even though I had it dialed as low as it would go. It has an adjustable "on" temperature. Of course it has an AC compressor over ride to come on when the AC is on. But when that is off, it has to sense the actual temperature of the radiator.

So the other day I came up with the idea to put heat sink compound on the probe. What a difference. It comes on about 30 degrees sooner then ever before.

So if you want better sensing of temperature, try heat sink compound. Available at any Radio Shack.

Re: For those with aftermarket electric cooling fans
 

You can also just buy a temp switch that screws into a coolant passage. It's not that expensive and works way better. I used this one from Painless Wiring.

www.summitracing.com/parts/prf-30103

Worked like a charm.

Re: For those with aftermarket electric cooling fans
 

Very interesting ideas, and that leads to the following question:

Which electric fan and what shop to order it from, for a 1988 Sierra GMC with a 350 TBI motor?

Re: For those with aftermarket electric cooling fans
 

I have used the sensor you speak about before however that grounds to pull in a relay. I'm not willing to experiment with the "probe" wire to see if that is how it actually works. I think it does not work that way since it has no ground on it.

I think it merely senses the temperature. If I went your way I would have to redo the control system. Not impossible just a lot more work

As far as suggestions for fan units. Well the price of an assembled unit has gone astronomical. There is this for example http://www.summitracing.com/parts/flx-280
For over 6 bills.

With regard to electric fans here's my take. First do not pin the fan to the radiator where the pins go through the radiator. The vibration will eventually loosen the fan and rub a hole in the radiator. If you can build a fan housing and build it with fan motors, fan blades and a control kit like Orange mentioned would be the least expensive way to go.

If you don't have plans for the housing, try to get people to let you see theirs for measurements. Mine has 2 fans and most do for our trucks. The design ultimately rests on the width of the radiator.

Good luck

Re: For those with aftermarket electric cooling fans
 

You are right about the price of the electric fans! I imagine that I could use an electric fan (s) from a Honda Civic or another at the local salvage yard. Yes, I would have to modify the housing, and buy a temperature sensor/control for it. Anyway, I am looking into some options.

By the way, I found some single fans that are a lot cheaper at Amazon.
Amazon.com: electric radiator fans: Automotive