Hey guys. Does anybody know the CFM on the stock fan. Anybody have suggestions for an electric fan upgrade. I have a 1998 Chevy Blazer 4.3l v6.

 

Not sure on the CFM for the stock mechanical fan, but I used an electric fan from a 99 Intrepid. It's a dual low/high fan that moves a lot of air, and it only cost me $40 from pick-n-pull. I wired mine to trigger based on AC compressor running, coolant temperature, and off a summer/winter switch. I also have a master kill switch so I can turn them both off (with a warning light) if I need them off for a water crossing or other such scenario.

I've had the efan in my 02 Sonoma for 6 months now, and the fan rarely turns on for temperature unless I'm sitting idle in traffic. I do have it wired so that when the ambient temperature stays above 20*C most of the time I'll flip the season switch so that one of the fans is on always, and then it will kick to high when triggered by the coolant temperature switch.

 

So is this ran off your computer?

 

No, I did not get my ECU flashed to control an e-fan, although that is quite possible. I have a mechanical temperature sensor from a port in the lower intake manifold beside the thermostat. I swapped to a lower intake manifold from a '99 Blazer (one that has accommodations for an EGR) because it had a plugged port right below the thermostat. I removed the plug and the port has the same standard thread as the factory temperature sensors. I bought a temperature sensor from Amazon that triggers at 95*C, then turns off again when it has cooled to 85*C. I just blocked off all the EGR ports in the swap LIM because my engine does not use an EGR.

 

Got any pics of this setup? I have electric fans in the works that I'd like to have controlled by the 0411 computer but before I swap to that computer I'd like to control the fans without buying a aftermarket controller before making the switch. I suppose I could just hook them up to a battery with a toggle switch in the interim but the electric fans supposedly draw a lot of amperage on startup.

 

I'm running a similar setup with the Intrepid fans. Mine are just wired to a 3 way toggle switch in the cab controlling 2 relays for high and low speed. They're wired to get power with ignition, with switch in one position has them kick on low speed, one position high speed, and the other position is just override off, useful for water crossings as mentioned above and also tinkering around under the hood when you need the ignition on but don't necessarily want the fans running.

I'd post pictures but I'm at work right now and our IT department has locked down our internet connection so much that I can't get PhotoBucket to load up properly and grab the links... so I can post some later this afternoon. My end goal was to have the setup look basically stock, like the truck could have came that way from the factory, and it came out pretty well.

 

Never know the wiser looking under the hood, unless you peaked around the upper fan shroud that I kept intact

 

You'll have to excuse my dirty engine bay. I just got back from wheeling through some muddy trails and haven't finished cleaning up.


This is my coolant temperature switch that triggers a relay to turn on the fan when it reaches operating temperature.

 

I tried a temp switch in the passenger side head for a while. Worked great, when it worked... Although I had the temp switch activating a relay, I had 3 switches fail in the matter of a year before I just gave up with that and wired them to a switched accessory power for the relay...

 

You need to make sure that you use a relay with a flyback diode built in, or add one to your wiring. If you don't the relay opening and closing will kill the temperature switch with voltage spikes. The flyback diode prevents the voltage spike on the trigger line from the temperature switch and protects it. In case you want to know what a flyback diode is, here's the Wikipedia article on them, and here's an article explaining why they should be used in circuits with relays. There's quite a few people on the S10Forum who have run into the same problems as you describe, and using a flyback diode on the relay solves the issue.

I've been using my cheap $15 Amazon temperature switch for about 8 months now without issue.