Just installed Hayden 3652 Fan switch and 97 T-Bird fan in my 77 w/302. Have made similar installations several times before. Verified fan, and installation correct but fan will not kick on when it gets hot. Tried another relay still not working. How can I check the radiator sensor/probe ? Have found that low speed on these fans is all that is required by direct wiring it. The temp comes down nicely that way and at least I can drive it.

 

Hi OR,
I'm not familiar with the Hayden products, but I've worked with Kenlowe and Lucas sensors before. Test the sensor like you would a thermostat... put it in a pan of water on the stove. You can monitor the water temp with a cheap cooking thermometer, or use a high-tech digital laser thermometer (those are handy to have in the toolbox anyway). With an ohmmeter hooked up to the terminals of the sensor, you should then be able to tell exactly when the circuit closes.

Good luck!
Karl

 

I pulled up the wiring diagram from Hayden's website to see what this thing is. Remove the YELLOW and BROWN wires from the radiator probe and short them together. Turn the key to RUN, and the fan should come on. My advice would be to short them together through a low-value inline fuse, personally - just in case. Or you can just use a jumper wire if you're comfortable with doing that.

If the fan does NOT come on, then something is wrong with the wiring, because this is the same thing as making the switch "think" the temperature is past the threshold.

If the fan comes on, then the wiring is fine, but the switch is not closing. This could be because the switch is bad, the temperature is not getting hot enough (which you can check with a temperature gauge), or the probe is not making good enough thermal contact.

Just my opinion, but radiator probes that go through the fins of the radiator are really not the way to go; personally I prefer a threaded sending unit. For my electric fan setup, I use a grounded-out switch threaded into the block that puts the sensor right in the actual coolant path.

 

fmc, will do that in the morning. Any idea what switch you used in water flow. Would rather go that route as opposed to this probe.

 

Here's the one I used. They sell a couple ON/OFF temperature varieties.

http://www.summitracing.com/parts/BCI-75029/

The wiring is a little different than the Hayden setup. The fan itself is powered through the relay just like the Hayden setup. However, in the Hayden setup, the relay coil is grounded at the relay, and power to the relay coil is what gets switched. In my setup, power is supplied directly to the relay coil from the ignition switch through a fuse. The relay coil gets grounded out through the temperature switch. When the temperature rises past the threshold, the switch grounds out, which closes the relay and turns on the fan. Pretty simple setup.

 

Went out with a flashlight and checked probe. OK. Went back over the whole darn thing again and the problem was a bad ground. Will go stand in a corner for a while as punishment. Sorry for the bother but thanks for the input. Will post pics of a very clean installation in the next day or so.

 

Awesome, glad to hear you got it worked out.