Electric fan and aluminum radiator questions 250 straight 6
 

So long story short, with the replacement of my old 250ci engine block, I changed the radiator & fan to an aluminum radiator and electric fan, and I upgraded the alternator.
I have a temp switch for the fan, but it comes on too late in my opinion (Reading on my meter says 120-130 C which would be 248-266 F when the fan comes on).
I don't want the fan to run permanently, but I also don't want to mess with the temperature switch.
I'm thinking that I should put a switch in the cabin and/or connect it to something like the brake lights.
Maybe there is something else I can connect it to in order to automatically turn it on/off?
Any thoughts/opinions?

Re: Electric fan and aluminum radiator questions 250 straight 6
 

Re: Electric fan and aluminum radiator questions 250 straight 6
 

http://i68.tinypic.com/sx2o1t.png


I have this and it works great.....easy to adjust in the winter months for where I live

Re: Electric fan and aluminum radiator questions 250 straight 6
 

Where is your temp switch getting the temp from? Why don't you want to mess with it?

Re: Electric fan and aluminum radiator questions 250 straight 6
 

That's way to high even on a BB motor. You want them to kick on around 195*. Are you sure that is the correct setting?
I have mine wired though the external adjustable temp senor in the fins to come on at 195* hooked to a relay straight off the battery. It is also hooked to a micro switch with a paddle to cut off at 35 MPH since you don't need the fan on at high way speed.
Link is for the adjustable switch.:chevy:


https://www.finditparts.com/products...SABEgJGdPD_BwE

Re: Electric fan and aluminum radiator questions 250 straight 6
 

Ok, so I took my multimeter and measured the resistance across the temp switch, and it seems low enough when hot.
I think the issue lies with it's power source. It was connected to the negative side of the coil. I have no idea how it came on at all, as it makes no sense to me. (maybe someone can explain?)
Can anyone tell me where the closest ignition wire would be? The other side of the temp switch is connected to the relay, which is connected to the ground.

Re: Electric fan and aluminum radiator questions 250 straight 6
 

On the fuse block, there should be a connector for IGN UNFUSED. Use this, put a fuse as close to the connection as possible, run that to the switch. 5A fuse should be sufficient, signal for the relay doesn't draw much.

Re: Electric fan and aluminum radiator questions 250 straight 6
 

Thanks! I currently have it wired to a in-cabin switch connected directly to the battery, as it seems the temp switch just doesn't work for some reason. My multimeter also seems to be broken, as I can't get proper measurements from it to verify the issue.
I tried putting resistors in parallel with the temp switch (started with 1k ohm down to 127 ohm), but the resistance still did not get low enough to activate the relay. I will get myself a new multimeter and measure again before I get a new temp switch. Just going to run it with a switch to IGN so that I can turn it off as needed for now.

Re: Electric fan and aluminum radiator questions 250 straight 6
 

The temp switch for the fan should act like a switch - on or off. A sender (to run a gauge) or sensor (for an ECU) will have different resistances based on temperature. The switch should be off when it is below a certain threshold, and on above it. There should be an adjustment on it somewhere to set that threshold.

For testing purposes, you could run one side of the switch to ground and the other side to a light in the cab. That way you can see what temp it is turning on / off at. If it has an adjustment screw on it, you can turn that to set the on / off temp.

what temp switch do you have? Do you have a manufacturer / model?