Well-Known Member
Just had a guy come in the shop and his new Derale dual fan controller wasn't turning on at all. Upon closer inspection, I noticed the temperature probe was stuck between the fins, but the cylinder it is attached to (that houses the thermocouple) was about a half inch from the radiators tubes. The instructions don't mention anything about that, but there is such a small area of the probe that's attached to the thermocouple housing, if there isn't enough contact area from the tubes to that small cylinder, the cylinder won't get hot enough to trigger the fan(s), or they won't turn on until a much higher temp.
You are also better off with the wire end of the cylinder facing the hot (engine side) of the radiator and the wire housing up against the tubes, not just the fins.
I wonder how many of those get poop canned or returned because of that?
How come the temperature probe isn't in the coolant flow ?? Getting the temperature for the outside of the cooler housing doesn't sound right .
I have one of these on my drag car Dodge. Originally I originally had a sensor stuck in the coolant via a threaded port. Then I for some reason or another I bought the fin probe kit with an adjustable rheostat power switch when I upgraded the rad fans to dual.

With the rheostat I can set it to turn-on or off at whatever temp I want, not dependent on the fin temp so much, as I can turn it on early or late via the rheostat. So the thoughts on not getting an accurate temp are moot. I can have it turn on when my temp gauge in the panel reads whatever I like. It took minutes to install. Easily adjustable. That is probably why it was chosen.

Nice Dart, Mr. MICHAEL! What power? How fast? I've had 2 1973 Dusters, a 70 Demon, a 73 and 75 D 100, 70 Sattelite, and a 79 Lil RED Express. All built! In addition to the 2 1987 GNs and my current Turbo T Limited, and a bunch of others. Love the A bodies and trucks!
I just ripped off all of the aftermarket, UGLY fan wiring and connected them up to run off of the stock fan relays, hi, lo, and cool down. I ran a wire from the original 3 pin plug to each fan
(2 hots and ground), and since the original fan uses the second (high) relay to bypass the internal resistor in the original fan, it turns off the low relay, so, I ran a diode from the hi fan output to the low relay coil. That way the low relay stays energized to keep my low fan on too.
Eliminated 13 feet of random wires!

I will be installing this here very soon to update/clean up my fan wiring. Full blow both fans.
I use a manual switch and an electric water pump to cool things down quickly:

The computer does all of that, why bother?
Ya want a manual turn on? Ground the green/yellow wire on the fan relays for manual on.
My car had 2 relays, a switch, and 28 FEET of wires to run the aftermarket fans on the Iceberg setup!
I ripped it all out and connected the fans, one to each factory relay, it works fine.
If u want both fans together whenever one is on, connect the green/yellow wires together. Then if u want manual, ground them with a switch.
I got that from the statement: not running a stock engine harness.
Ya might have led with that, or did I miss that....
I have issues with my employees all of the time, they know what they are thinking, and I don't. NO sweat!
Do you not have a youtube "presence"? I bet you have a phone that makes vids. Easy to upload. Then just copy the link and put it in the message and wala a vid is born.