aux fan
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Senior Member
Joined: Jul 2011
Posts: 515
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From: ogden, utah
Year: 2000
Model: Cherokee
Engine: l6
aux fan
So I hooked my auxiliary fan up to a toggle switch inside. I need to know which way it should spin because reversing polarity makes it spin different ways and it was never hooked up before so I don't know which wire was true positive. If looking at the Jeep head on, should the fan spin clockwise or counter clockwise???
CF Veteran
Joined: Apr 2011
Posts: 14,553
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From: Carrollton, GA
Year: 1994
Model: Cherokee
Engine: Inline 6 4.0L High Output
Never heard of it going backwards... I think the motor will only turn one way... because of the way its wired up i dont think its even possible without some heavy witchery
CF Veteran
Joined: Aug 2011
Posts: 10,489
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From: Nor-Cal Coast
Year: 90,84
Model: Cherokee
Engine: 4.0,2.5
Generally a DC motor will reverse with the wires the other way, Also it will become a generator, if you drive it and it's hooked to a lower voltage than it's pushing. (really). Of course you want it hooked up to blow font to back, with a fuse on the pos side.
CF Veteran
Joined: Sep 2011
Posts: 4,172
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From: Riviera, Texas
Year: 1998 Sport
Model: Cherokee
Engine: 4.0
You want it to pull air into the engine. If you can't figure out which is positive. Just run a temporary wire from one side until you get the air flowing into the engine compartment. And, Yes. They will flow in both directions. I found this out when I installed 2 in my 65 Chevy P/U.
Seasoned Member
Joined: Oct 2009
Posts: 416
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From: Tucson AZ
Year: 94
Model: Cherokee
Engine: 4.0
Look at the fan blades, they are twisted at an angle front to back. the side thats points towards the front of the Jeep is also pointing in the direction it needs to turn.
Thread Starter
Senior Member
Joined: Jul 2011
Posts: 515
Likes: 1
From: ogden, utah
Year: 2000
Model: Cherokee
Engine: l6
I know they can definitely turn opposite ways with switched polarity. I got it set to blow towards the engine. Thanks guys. I can't believe I never had it hooked up... oops ha
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CF Veteran
Joined: Apr 2011
Posts: 14,553
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From: Carrollton, GA
Year: 1994
Model: Cherokee
Engine: Inline 6 4.0L High Output
^^This^^
You want it to pull air into the engine. If you can't figure out which is positive. Just run a temporary wire from one side until you get the air flowing into the engine compartment. And, Yes. They will flow in both directions. I found this out when I installed 2 in my 65 Chevy P/U.
You want it to pull air into the engine. If you can't figure out which is positive. Just run a temporary wire from one side until you get the air flowing into the engine compartment. And, Yes. They will flow in both directions. I found this out when I installed 2 in my 65 Chevy P/U.
CF Veteran
Joined: Aug 2011
Posts: 10,489
Likes: 24
From: Nor-Cal Coast
Year: 90,84
Model: Cherokee
Engine: 4.0,2.5
CF Veteran
Joined: Apr 2011
Posts: 14,553
Likes: 1
From: Carrollton, GA
Year: 1994
Model: Cherokee
Engine: Inline 6 4.0L High Output
CF Veteran
Joined: Aug 2011
Posts: 10,489
Likes: 24
From: Nor-Cal Coast
Year: 90,84
Model: Cherokee
Engine: 4.0,2.5
Oh, OK. Thought you might have "special knowledge" into the inner secrets of Permanent magnet DC motor/generators. I have one that is burning up, going through one brush, and leaving the other OK. They are at 90* and it is the trailing one on rotation. I buy new "sets", then just use one of the pair, Go through three before the other wears out. 
CF Veteran
Joined: Aug 2011
Posts: 10,489
Likes: 24
From: Nor-Cal Coast
Year: 90,84
Model: Cherokee
Engine: 4.0,2.5
Yea...I didn't add, it started after being fine for about 5 years. Being it's on 300' of wire, (600' both ways), I thought maybe some sort of resanence, or spikes or something. I added a points condenser, (for lack of a better idea), no help. It's not spring pressure. The commutator is just as smooth for one as it is for the other...
Last edited by DFlintstone; Jul 1, 2012 at 12:36 PM.