Electric fans 02 pathfinder

[Mbrianc]

Did you have to install a diode to keep from backfeeding the relay when the fan is off and you are at speed?

 

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[XPLORx4]

No diodes needed; the fan is controlled by an automotive relay.

 

Terminal #30: battery +

Terminal #87: fan +

Terminal #85: feed from A/C compressor

Terminal #86: ground

 

When the relay isn't engaged (no power between 85 and 86, ie. when AC compressor is off), the circuit between the fan (87) and the battery (30) is open, so no current flows either direction.

[hawairish]

This is actually how I have my Pathy configured. I have the stock belt-driven fan and clutch, and a 12" pusher mounted in front of the AC condenser. It runs only when the AC compressor is on.

 

Sorry to tangent a little, but would there be an added benefit to having this supplemental fan wired run under both conditions, at x° temp and with AC? Seems like that would cover low speed, hot weather applications pretty well.

[XPLORx4]

Sure, it could be wired to come on at x° temp, but:

A.) it's harder and more costly to add a thermostatic sensor for this purpose

B.) it doesn't cover much of the radiator, and covers less than 1/2 of the AC condenser anyway.

C.) when it's hot enough to need the fan, the AC is likely going to be on, too. The stock belt-driven fan is plenty powerful enough to keep the engine cool at idle, but it sometimes does not pull enough air to cool the AC condenser AND the radiator, so the AC may blow not-so-cold air at idle on very hot days. This is why I installed the fan in the first place.

 

What I would like more than turning the fan ON at x° temp is to turn it OFF at x° temp or speed, regardless if the AC compressor is running. The fan doesn't really need to run when the car is moving, but I haven't really devoted much research into how to make that happen. The best I came up with is modifying a small PC or USB fan to become a generator so that at a certain speed, air movement spins it fast enough to generate enough power to trigger a micro-relay which breaks the circuit between the compressor and main fan relay.

Edited March 11, 2017 by XPLORx4

[Citron]

That would give you air speed, not ground speed, which could vary greatly if you a heading into a strong head wind.

 

Is there something that comes on at a certain speed? In newer cars when in drive and above x speed, it automatically locks the doors. Does the pathy have any circuit that changes state based on a defined speed point? Does it auto lock the doors? If you can find one, grab that output from the ECM and use it to turn the fan off at that speed.

[XPLORx4]

That would give you air speed, not ground speed, which could vary greatly if you a heading into a strong head wind.

 

Is there something that comes on at a certain speed? In newer cars when in drive and above x speed, it automatically locks the doors. Does the pathy have any circuit that changes state based on a defined speed point? Does it auto lock the doors? If you can find one, grab that output from the ECM and use it to turn the fan off at that speed.

 

I'd actually prefer air speed, since that's what's keeping the AC condenser cool.

 

As for ground speed (measured by the Vehicle Speed Sensor), my model/year Pathfinder actually doesn't have anything that gets triggered by the body-control module at a certain speed (such as door auto-lock), or I'd surely have found a way to use that output. That's why it seems easier to modify a small fan to become a generator.

[Mbrianc]

Perhaps one of those paddle airflow switches from an HVAC system or a dryer to open the control circuit on the relay?

 

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