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post #1 of (permalink) Old 05-28-2004, 08:29 PM Thread Starter
 
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Electric fan control?

I am looking for a thermal switch to control my electric fan.

Flex-Lite has them, but they are $85 a peice.

NAPA has OEM ones for cars and trucks, but there are no descriptions or wiring diagrams. I'm wondering if anyone has any info on this.

I want a sensor that plugs into the water jacket, and turns the fan on when the engine is overheating.. (whats the temp for an engine to be classified as "getting warm")

Napa has a standard Chev one that will screw right into my jacket.. it's got 2 leads comming out of it thought, anyone know how these work/how its wired.

Part numbers would be GREATLY appreciated.

Anyone?
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post #2 of (permalink) Old 05-28-2004, 09:26 PM
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Re: Electric fan control?

This one has always worked good for me. They have other adjustable ones also.
Typically they are wire hot in one side, out the other to a relay to the fan, when they get to a certain temp, they close the contact and send the 12v to the relay triggering the fan.
speedway motors fan switch
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post #3 of (permalink) Old 05-28-2004, 10:11 PM Thread Starter
 
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Re: Electric fan control?

Looks familiar.

Did any jeeps from 1986-1989 have electric fans, because the part was listed for those years too.

I would assume that the switch for the Chev engines whould be set to whatever they're supposed to run at.. there's not mcuh reaosn for a 2 pole switch for anything else is there?
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post #4 of (permalink) Old 05-28-2004, 10:13 PM
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Re: Electric fan control?

pbmcauliffe has the parts down.

There's another reason to always use a relay to power your electric fan(s). If you connect them directly to the battery through a thermal switch the motor will not shut off when you turn off the key if the thermal switch is closed. Why is that you might ask... simple... the fans turning act as a generator and supply voltage back to the ignition keeping the motor running until the fans spin down.

So it's kinda simple...

+12 to relay contact, other side of relay contact to fan(s)
other side of fan(s) to ground
+12 to thermal switch, other side to coil of relay
other side of relay coil to ground

Sorry that I can't draw a schematic... haven't had a CAD program in years (funny I don't often miss that).

Good Luck

Dale
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post #5 of (permalink) Old 05-28-2004, 10:23 PM Thread Starter
 
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Re: Electric fan control?

Ohh.. more questions now.

I wanted to wire it to a 3 way switch.

Position 1: Off
Position 2: Lowspeed Automatic
Position 3: On

I hope i won't need the high speed setting, if I do I'll hook it up to another switch perhaps with another relay.

Can I use a relay to stop the fan becoming a generator, or do I have to use another elctrical component. (don't know the name of it.)

Also, should it be hooked into the ignition or the live all the time.

Is it important for the fan to cool the rad after the engine stops running? My friends Scirocco does.. but only for like 5 seconds.
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post #6 of (permalink) Old 05-28-2004, 10:45 PM
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Re: Electric fan control?

</font><blockquote><font class="small">In reply to:</font><hr />
I wanted to wire it to a 3 way switch.

Position 1: Off
Position 2: Lowspeed Automatic
Position 3: On

[/ QUOTE ]

OK, I'm guessing here but the fan has three wires and two modes?? If so that would make for some options....and more info is required.

If the fan only has two wires then here are the only options I can think of.

Position 1: Off
It's off, nothing to talk about here.

Position 2: Lowspeed Automatic
Wire as described above.

Position 3: On
Hook up a toggle switch that supplies +12 to the relay coil even if the thermal switch does not.
+12 to the toggle switch, the other side to the wire from the thermal switch to the relay coil so that it over rides the thermal switch.
Kinda seems like a manual override.

Does the fan have a lowspeed and highspeed connection?
Two thermal switches would make that pretty hard to beat. One that connects to turn on the fan in normal conditions (Lowspeed Automatic) and yet a different thermal switch (higher temp turn on) as a fail safe that turns the fan on at a higher speed when the motor is getting over heat.

The second circuit would be simply redundant and wired the same with a different thermal switch and relay.

Dale
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post #7 of (permalink) Old 05-28-2004, 10:49 PM
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Re: Electric fan control?

</font><blockquote><font class="small">In reply to:</font><hr />
I wanted to wire it to a 3 way switch.

Position 1: Off
Position 2: Lowspeed Automatic
Position 3: On

[/ QUOTE ]

1. Here ya go.


</font><blockquote><font class="small">In reply to:</font><hr />
Also, should it be hooked into the ignition or the live all the time.

[/ QUOTE ]2. If you want the fan to run in Ignition mode OFF,
3. Then yes...</font><blockquote><font class="small">In reply to:</font><hr />
Is it important for the fan to cool the rad after the engine stops running? My friends Scirocco does.. but only for like 5 seconds.

[/ QUOTE ]
4. It can be important.
5. A fan running till the engine block is cool,
6. Even after the engine's turned off,
7. Isn't a bad thing...
8. Just remember how it's wired..
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post #8 of (permalink) Old 05-28-2004, 11:08 PM
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Re: Electric fan control?

[img]images/graemlins/goodpost.gif[/img]

LEVE has it, I wasn't thinking past the "Lowspeed" thing and got caught up in the redundant thermal switch idea also.

But here is a question about the configuration in your schematic LEVE:

Why is there an OFF mode? When would you ever want to shut the fan down during normal operation?

And as an after thought, fuses would be a good idea.

Dale
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post #9 of (permalink) Old 05-28-2004, 11:18 PM
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Re: Electric fan control?

</font><blockquote><font class="small">In reply to:</font><hr />
Why is there an OFF mode? When would you ever want to shut the fan down during normal operation?

[/ QUOTE ]1. Normal?
2. That can be a qualifier...
3. However, how about...
4. Low speed trail crawling,
5. Temps outside at about 100* F,
6. Or above,
7. Engine heats and fan comes on.
8. You approach a water crossing,
9. And can't turn the elect fan off.
10. It's on as you enter the water,
11. And it eats the radiator.
12. I'd prefer that not to happen.
13. So there's an option to turn it off.
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post #10 of (permalink) Old 05-28-2004, 11:26 PM
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Re: Electric fan control?

Well OK.... just another thing that I didn't think of.

Nice to have so many folks thinking for you.

Heck I wouldn't think to flip the switch and turn off the fan.

Dale
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