Nicram

As topic says can I run two fans on one pin?? I got no AC and the fan for AC is not hooked up, can I hardwire it to the radiator fan? If so do I need to change the fuse? Will the rpms will be the same as they would be running on one pin?

mike1114

iTrader: (1)

I did this, obviously they are not going to spin as fast since they are sharing the same line of voltage, but it didn't seem to make that much difference.

I only noticed that they started up slower, once spinning, i couldn't tell the difference from one fan vs. two with the naked eye.

Nicram

Anyone else? How drastic is the rpm drop? I am sure there is a nice formula for this!
I got a twin FAL fans, it would suck not to use the full capability of those fans...

Relic1

as long as the relay that drives it can hold both go for it.
what are the current ratings on the fans that you have? especially start up current.

Bakeoff

you have to understand electronics before you look at this.
You can:
A) splice off the positive and negative and run them in parallel. This will lower the resistance in the circuit. Neither fan should run slower for any reason other than a slightly higher amperage draw. But the alternator has enough output to cover this. Non-issue.
Or....
B) Run them in series. Cut off the negative coming back out of the original fan, run that to the positive of the second fan fan, and then run the negative back into the original harness. This will create more resistance on the circuit, and should run the fans slower. How much? All depends on the amperage rating on the fan.

Go with A and you should have a problem at all.

Nicram

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Bakeoff &raquo;</TD></TR><TR><TD CLASS="quote">you have to understand electronics before you look at this.
You can:
A) splice off the positive and negative and run them in parallel. This will lower the resistance in the circuit. Neither fan should run slower for any reason other than a slightly higher amperage draw. But the alternator has enough output to cover this. Non-issue.

Go with A and you should have a problem at all.</TD></TR></TABLE>

What point should I splice it at??

sicones

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Bakeoff &raquo;</TD></TR><TR><TD CLASS="quote">you have to understand electronics before you look at this.
You can:
A) splice off the positive and negative and run them in parallel. This will lower the resistance in the circuit. Neither fan should run slower for any reason other than a slightly higher amperage draw. But the alternator has enough output to cover this. Non-issue.
Or....
B) Run them in series. Cut off the negative coming back out of the original fan, run that to the positive of the second fan fan, and then run the negative back into the original harness. This will create more resistance on the circuit, and should run the fans slower. How much? All depends on the amperage rating on the fan.

Go with A and you should have a problem at all.</TD></TR></TABLE>

maybe you should learn electronics first before you start giving advice

to OP go find how to use one of these


/thread

Slurp56

Agree'd. A relay is the way to go. SPDT relays can be had for under $5 and can be bought at any parts house or car stereo shop. I tried this same setup and popped my fuse. Didnt realize it until I was in traffic and started seeing steam.. doh! I was also on a road trip, so I think I had to "borrow" a fuse from one of my head light circuits till I could get the to parts store and buy more.

Nicram

So...... I need to run it by a relay??
Could someone just draw out a simple diagram please??

Slurp56

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Nicram &raquo;</TD></TR><TR><TD CLASS="quote">So...... I need to run it by a relay??
Could someone just draw out a simple diagram please??</TD></TR></TABLE>

Sure!


Tap the power wire from your fan to one post of the coil and ground the other. Then run a wire from your battery positive terminal to the new fan and then run the fan ground to the common post on the relay, then run a wire from the NO (Normally Open) post to chasis ground.

Nicram

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Slurp56 &raquo;</TD></TR><TR><TD CLASS="quote">

Sure!


Tap the power wire from your fan to one post of the coil and ground the other. Then run a wire from your battery positive terminal to the new fan and then run the fan ground to the common post on the relay, then run a wire from the NO (Normally Open) post to chasis ground.


</TD></TR></TABLE>


Huh....??? Sorry my knowledge of elctricity is not as advanced.

Writing it in a a languge that I would get you mean to
Taping into the positive wire going to the fan and running it to the relay post and grounding the other post , then running a positive straight from the battery into the fan #2 and hooking up the ground of fan # 2 into the relay and grounding the Normally Open post to the chasis. Correct?

Relic1

the simple answer to this... splice the second fan's wires to the positive and negative of the other fan and you'll be fine.
honda use a 10 amp relay in the underhood fuse box to drive the normal fan so there is no need for another relay.
reason why I know this works... integras use two fans wired to the identical relay all the time. And after some searching I found that the FAL fans actually draw less power than the OEM fans.

Nicram

Thanks!!!

So just negative to the working fan and the positive straight from the battery?

Relic1

the existing fan has two wires, connect the second fan to those two wires. positive to positive, negative to negative.

dek1mfk

i did the same thing to my fans for almost a year and it still worked good when i pulled out the old engine so im guessing it shoudnt be a problem.

gotbooost

Using a relay is still the right way to do it.