yet another DC Controls question

[GregD]

Just a quick question I'm hoping someone can answer. I completed the wiring of the electric fan and DC Controls unit. However, I did not use the yellow wire at all thinking that it was only needed if I wanted the fan to shut off immediately when the ignition is turned off. My thinking was that without the yellow wire, my fan would continue to run after the ignition was off until the coolant temp reached the set point.

However, after reading through the instructions more closely, it looks as though the yellow wire should be wired to a constant 12v source if you want the fan to continue to run after the ignition is off. My question is, is this really necessary? my fan seems to work fine without the yellow wire. It continues to run after the ignition is off and will eventually shut off once it reaches the setpoint. Should I wire the yellow to a constant 12v source or leave it alone?
Thanks,
Greg

[CAMAROBOY69]

EDIT:
deleted incorrect information. This is the CORRECT information.
Yellow wire attached means the fan will run with ignition off.

[GregD]

I am also installing the DC controller and its almost done. (had to wait for new surge protector) My understanding is that if you hook the yellow wire to the ignition it guarantees the fan will shut off with the ignition off. I want mine to shut off with the ignition so I will be hooking my yellow wire up for sure. Hope that helps.

Adam, I'm in agreement with you that you need the yellow hooked to switched 12 volt if you want it to shutoff when you turn off the ignition. But do I need it wired to a constant 12 volt if I want the fan to continue to run after the ignition is off until it reaches the setpoint temp? Seems to do be doing what I want without the yellow wire but I want to make sure I am not damaging anything or causing other issues without it.
thx

[CAMAROBOY69]

That would be a question for Jabin. I barely know the basics of how this controller works.
Oh yeah quick question for you. How did you keep your probe from falling out of the radiator? I put silone on mine because it just seemed to fall out otherwise.

[GregD]

my probe barely fit in between the fins on the radiator. I had to carefully open up a gap between the fins with a flat blade screw driver in order to get the probe in there. Its a very tight fit so I didn't need anything. I would think that the silicone would be fine as long as it doesn't act as an insulator on the probe.

Hopefully Jabin will chime in here.

[TD509EFI]

Here's the instructions I have from DC Controls:

"For continued cooling AFTER engine shut-off, connect the yellow ignition input wire of the harness to the unit and to any 12v source".

If you don't want the fan on after you turn of the ignition, don't hook up the yellow wire. thats' how I read it.

John

[gmachinz]

John is correct. Connect the yellow lead if you want after ignition run-on. -Jabin

[CAMAROBOY69]

Thanks Jabin. I guess I will leave my yellow wire off too so the fan will shut off with the ignition.

Ignition input

-For continued cooling after engine shut-off, connect the yellow ignition input wire of the harness to the unit and to any 12 v source.
-If an Immediate shut off is required, connect the yellow ignition input wire of the harness to the unit and to any source that is 12 v whenever the the ignition is on.

[CAMAROBOY69]

Wait a minute. Read gregs post again. he said the fan keeps running and he DOESNT have the yellow wire hooked up.
But you say to leave it off and the fan will shut off right away.

[Jagarang]

I wondered why everybody was missing the point? He's getting run on without the yellow wire connected.

[GregD]

I wondered why everybody was missing the point? He's getting run on without the yellow wire connected.

Exactly!!

[baskin]

The yellow (ignition input) wire has a very small bias on it so that it will default high if it becomes disconnected, using the U/D disables the feature so that the fan won't start running if the car is parked and the connection to 12v is lost.

It doesn't hurt antyhing to leave it off, but some of the pins on the 16 pin connector are connected to the ign input, so if the 16 pin gets a lot of contamination from coolant or dirt, the conductance through either will shut the unit off.

[rockdogz]

Just curious why you would want to force the fan to turn off when turning the ignition key off, instead of allowing it to continue to run?

[baskin]

Almost no one hooks them up that way, the oscillator was tuned on the mark viii fan to give a pleasent tone while it ramps down, and that works pretty well for most all of the fans, but if the fan happened to have a mechanical resonance near that frequency band, it would probably still be masked by the engine noise but could be annoying after the car is shut off, so that's why the option is there.

[CAMAROBOY69]

Just curious why you would want to force the fan to turn off when turning the ignition key off, instead of allowing it to continue to run?

1. I would be too worried it wouldnt shut off. If I walk away from my car I dont want to hear anything running at all.
2. Its still sucking battery power if it is still running.
When I turn my key off I dont want any life left in my car. Nothing.

[cad]

I've got the yellow wire hooked up to 12v on mine.
It only runs a minute after the key is off. I planned to leave it that way. I think it will be fine and it will prevent a little bit of what some refer to as "heat soak" on a hot day after you shut it off.
And, btw, it makes a very strange, yet cool, whine noise while it winds down....

[GregD]

I've got the yellow wire hooked up to 12v on mine.
It only runs a minute after the key is off. I planned to leave it that way. I think it will be fine and it will prevent a little bit of what some refer to as "heat soak" on a hot day after you shut it off.
And, btw, it makes a very strange, yet cool, whine noise while it winds down....

Thats what mine does too.. but I'm not using the yellow wire.