I've read somewhere on teh interwebs where someone measured the outputs of various efans. Of those tested, the CFMs of the intrepid/concorde fan was slightly higher than the taurus fan.

The easiest way is to wire in a temp switch and a relay for the low speed and a manual switch for the high speed. Or wire the high speed into your AC, so when the AC is on the fan is in high. There are several wiring diagrams on the net for adding an efan. S10Forum has a few that will work well depending on your preferences(all auto, some auto or all manual controls). There are even a few efan kits that come with the components, diagram and instructions.

Something to keep in mind, your '02 should have the 0411 PCM. I think it appeared in all '01 and newer 4.3L S-series vehicles, and tons of full size vehicles It is the silver box sitting under the rubber mallet in this pic:

If you looke closely, you can see the pink and yellow wires I selected for the efan seperated out from the already modified harness. Please disregard the disarray of my engine compartment, that pic was in the llater stages of replacing my LIM and head gaskets and I to be able to move the Blazer in and out of the shop.

The 0411 PCM, among other things, has the capability to control an electric fan. In the Blazers, I do not believe it is activated or pinned for it, but that can be remedied. Addidng the pins for high and low speeds is easy, but I think activating the controls needs the PCM to be programmed by an aftermarket tuner. I cannot say whether the dealership can activate this feature for you, custom modifications to the PCM are generally outside of theservices that a dealership provides. Unless you have an 'In' at the dealership that is willing to try for you, I would suggest that you not try the dealership, because it will be an expensive waste of your time.

This PCM can be swapped into earlier trucks with a few hours worth of effort and a reprogram. Having done it, it is not something I would do just for an efan.

 

can you describe how you did this? Where did you wire for power and ground and what type of controller did you use? Where did you wire the switch through? In to the cabin through the firewall?

 

When I bought my jimmy I noticed an engine vibration, upon inspection I found a couple missing fan teeth and decided to go electric. I used a spare ZX2 fan I had and it worked well until at the sand dunes I hit a rut and the sudden stop dislodged the fan and it bored into the radiator.

I replaced the radiator and fan with a flush mount 16". it again works but not to well in high heat conditions. I would recommend 2 smaller fans.

Napa or really any auto parts store carrys a temp switch. its adjustable and uses a temp probe in the radiator then works like a relay. I wired in a switch to jumper the temp switch and now I have control. I plan to hook into the a/c system to. so when a/c is on, the fan will also come on.

 

My clutch fan shaft snapped and my radiator fan took out the radiator and the shroud. It also left shrapnel all over the engine bay from the plastic blades flying apart. this is on my 02 blazer. I used to own a 99 blazer that kept giving a vibration through the clutch fan shaft and would always cause premature failure of the water pump.

My equation for a fix. Concorde electric fans with a brand new stock radiator from Napa. The Concorde fans were from a 99 or 2000 Concorde. Took about 2 hours to modify the shroud with a Dremel and a cutoff wheel. I removed all four side brackets from the shroud and trimmed back about a half of an inch on both sides of the shroud. I just took away back to where the plastic started to turn downward towards the radiator. That was enough for it to drop right in snug between the plastic side tanks on the radiator. I used a derale plastic mounting kit that you just drill four small holes through the corner of the shroud and run the straps through the radiator and pull it in tight. I also put a bolt in the bottom and the top of the shroud through the metal bottom and top rail of the radiator. It doesn't move at all.

For a fan controller I went with the painless 30141. It is a single fan controller. If you look at how the intrepid/Concorde fan is wired, it made sense to use this controller. There are four wires at the end of the oem fan harness which go to a stock plug you cut off anyway, because this went in a blazer and not a Concorde. The wires are green and yellow for positive. Black and blue for ground or negative. I ran green and yellow together to the single positive side of my single fan controller. The black and blue wires were joined together and ran to the negative post on the battery. All wiring was soldered and heat shrunk and loomed. The painless single fan controller can handle 70 amps and starts the fans up at 50 percent speed. It then can raise the speed of the fans gradually to 100 percent as needed through pulse width modulation. With the green and yellow wires wired together I'm controlling the high speed side of the fans but starting at 50 percent by using this controller.

So far the results are impressive. It comes on with the ac and has programmable speed override. I set my fans to turn off at 36mph. They will turn back on automatically at a speed above 36 if the temperature reaches at least my preset turn on temperature. I have mine to come on at 50 percent at 210 degrees and reach full speed by 235 degrees. It cools so well that my fans only run for a few seconds at 210 degrees and then stay off for awhile.

I'm using the stock 195 degree thermostat and have wired the temp sensor that was included with the fan controller. I removed the coolant plug from the passenger side head and installed the temp sensor into that location. It is halfway back on the passenger side head and right by the dipstick tube, so you need to move the dipstick tube back some by removing the retaining bracket bolt.

All in all this project was kind of a pain, time consuming, and not very cheap but I could not be happier with the results. The truck runs at a rock steady 210 degrees in the summer heat with the ac on. Now I don't have to worry about any more fans flying off or water pumps going bad early. Plus I picked up about 1mpg by going electric.

 

This is how I wired my fan