[bdmonist]

Alright - The other thread wasn't getting much attention, probably because the name didn't reflect its content

Here's the deal - I have a dual Ford Countor Fan setup on my 350 in a CJ7. I want to wire it to a switch for Auto, OFF, and ON. I am certainly weak on electrical and would like some suggestions - Here is the wiring for my Torqflo controller

The green a/c wire turns the fans on regardless of the temperature...
Will this get me where I want to be? This is the only way I can figure out how to get power to the yellow and not the green and still be able to get the ON function using the switch. Doesn't a diode act as an electrical check valve

SPST Five Terminal Relay (I think they should both be 87's, not 87a)

There just seems like there should be an easier way. Thanks in Advance.

[jscherb]

Seems like a simple DPDT center-off would do the trick, I think you're making it more complex than it needs to be.

Here's what's important:

1. if there isn't any voltage on either the "ignition source" or the "AC Clutch" leads, the fan won't run

2. the fan will run automatically is there is 12v on the "ignition source" lead.

3. if there is also 12v on the "AC clutch" lead, the fan will always run

Both "ignition source" and "AC clutch" are inputs to the controller, I don't believe you need to isolate them from each other with a diode or relays, although I've never used this particular controller before.

Here's how the switch would be wired:

Center would be off per rule 1 above.

Flip it one way and it would connect power only to the "ignition source" lead, that would be the "Auto" position per rule 2.

Flip it the other way and one pole connects 12v to the "ignition source" lead and the other pole connects power to the "AC clutch" lead per rule 3.

Do you need a diagram or is that enough info?

You could also wire it differently to include LED status indicators (an LED to indicate "Always Off" would be a good idea.) But first get it working as above and then you can get fancy.

[jksull]

Yes a Diod only lets current go one direction
Do you want both fans on in the on position of the switch

[Stan99]

Sorry the other thread was just to see if the first thread was till going and I wasnt just having a brain fart. But I am glad to see another thread on this subject going. This will be the first thing I start to wire when I get my tub on this weekend. WHere did you get the controller at?? I have dual 10" fans that I am running for my 258. I want an automatic one like you have but dont know if that controller will handle the two fans. Please let me knopw what you think I should do?? Here is my set up without the shroud.

http://s244.photobucket.com/albums/gg7/stantycole/Fans/?action=view&current=PICT0347.jpg

[Aggie99]

I just did mine and am using the same controller that you have. I ran the fused red wire through the fire wall and into the cab. I then found an unused wire that is a 12V constant from the battery. Using a cheap 3 position switch from Autozone that had 2 ACC poles and a constant pole, I wired the fan in. Wire the Fused red from the fan to the constant pole in the center and the 12V constant to either of the ACC poles. By doing this, I have power until the fan is switched opposite from the 12 V constant. This way, you are not leaving the switch in the "On" position all the time. You are turning it "On" to kill the fan for a water crossing.

[bdmonist]

See Bold Below

Originally Posted by jscherb

1. if there isn't any voltage on either the "ignition source" or the "AC Clutch" leads, the fan won't run TRUE

2. the fan will run automatically is there is 12v on the "ignition source" lead. TRUE

3. if there is also 12v on the "AC clutch" lead, the fan will always run TRUE

Both "ignition source" and "AC clutch" are inputs to the controller, I don't believe you need to isolate them from each other with a diode or relays, although I've never used this particular controller before.

Here's how the switch would be wired:

Center would be off per rule 1 above. - Got this

Flip it one way and it would connect power only to the "ignition source" lead, that would be the "Auto" position per rule 2. Got this

Flip it the other way and one pole connects 12v to the "ignition source" lead and the other pole connects power to the "AC clutch" lead per rule 3. This is where you lose me - Wired this way, when I flip the switch to RUN and power up the AC wire using the switch, don't I lose the power to the igniton wire? Or am I just not familiar with this type of switch?

Do you need a diagram or is that enough info? If you can answer the above question I'll be OK without - Unless you have some free time

[bdmonist]

Originally Posted by jksull

Yes a Diod only lets current go one direction
Do you want both fans on in the on position of the switch

YES.................. <----10char

[jscherb]

I drew a diagram for you showing two ways you can wire it.

The top diagram is a simple way to use a DPDT Center Off switch to provide AUTO, OFF and ON with the controller you're using.

The bottom diagram should also work with your controller although since I don't have that controller I cannot test it. It has an LED to indicate when the system in in OFF mode, to provide a warning that you're not cooling the radiator. This uses an ordinary LED as the warning indicator (note: the circuit will NOT work with a "flasher LED").

Jeff

[bdmonist]

Sweet - That'll do it - Thanks a ton Jeff

[Mr.Crowley]

where did ya pick up that controller,and was it reasonable?Im not liking the one I have..

[jscherb]

Originally Posted by jscherb

I drew a diagram for you showing two ways you can wire it.

The top diagram is a simple way to use a DPDT Center Off switch to provide AUTO, OFF and ON with the controller you're using.

The bottom diagram should also work with your controller although since I don't have that controller I cannot test it. It has an LED to indicate when the system in in OFF mode, to provide a warning that you're not cooling the radiator. This uses an ordinary LED as the warning indicator (note: the circuit will NOT work with a "flasher LED").

Jeff

Someone asked me in a PM why the resistor is needed in the second diagram and what wattage resistor should be used. I'll answer it here because maybe others are wondering.

It serves two purposes.

1. When the switch is set for OFF, the 12v source goes through the resistor and the LED to ground. The controller input is between the resistor and the diode. The LED provides less resistance to ground than the resistor provides to the 12 volt source, so the controller input is "closer to ground" than it is to 12v and therefore the controller acts like it is grounded. Without the resistor, it will see the full 12v and won't turn off.

2. It limits the current through the LED. Putting 12v on an ordinary LED will blow it up. A 1k ohm resistor will limit the current to a safe level.

A 1/2 watt resistor will be fine.

Jeff

[jfwireless]

Just to add to Jeff's excellent description, a silicon diode exhibits a .6 volt voltage drop when forward biased or turned on, so when the switch is in the off position the ignition input to the controller is at .6 volts, when the switch is in the on position the ignition input to the controller is at 12 volts.

The current through the resistor is only 10 milliamps, so the power dissapation of the resistor is only .12 wats, so a 1/2 watt resistor is just fine.



Jim

[bdmonist]

Originally Posted by Mr.Crowley

Where did ya pick up that controller,and was it reasonable?Im not liking the one I have..

It's a Torqflo from Autozone. I think it was about $35 or so.

[jscherb]

Originally Posted by jfwireless

Just to add to Jeff's excellent description, a silicon diode exhibits a .6 volt voltage drop when forward biased or turned on, so when the switch is in the off position the ignition input to the controller is at .6 volts, when the switch is in the on position the ignition input to the controller is at 12 volts.

The current through the resistor is only 10 milliamps, so the power dissapation of the resistor is only .12 wats, so a 1/2 watt resistor is just fine.

Jim

Jim,
Thanks for the extra explanation, I'm sure that will help some people. Just one edit to what you wrote: this is an LED, not an ordinary diode, and the forward voltage drop of a red, green or yellow LED is in the range of 1.1-1.5 volts, so that's the voltage the ignition input will see.

BTW, a blue or white LED has a forward voltage drop of about 3.5 volts, so I wouldn't use that color in this application, that could possibly be too high and might cause the controller to switch on when you intended it to be off.

Jeff

[bdmonist]

Jeff - IN option 2, #3 - Why doesn't the ignition source get it's 12V from the bottom left node?