Any Electric Fan Setups Out There?

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Mike W.
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Seems BMW went to PWM fans starting in '99 on 5 series cars. A word of caution however, while I've put ~230K on those cars without an issue, the PWM part is not regarded as bulletproof. The fan itself is pretty good with failures rare, and some have been known to use PWM fans on plain 12V DC after the PWM part fails, but in junkyard hunting make sure you test it within the warranty period.


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VStar650CL
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Mike W. wrote:
Sun Aug 14, 2022 5:38 pm
The fan itself is pretty good with failures rare, and some have been known to use PWM fans on plain 12V DC after the PWM part fails, but in junkyard hunting make sure you test it within the warranty period.
Sage advice for any JY part. :bigthumb:

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VStar650CL
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Mike W. wrote:
Sun Aug 14, 2022 5:38 pm
The fan itself is pretty good with failures rare, and some have been known to use PWM fans on plain 12V DC after the PWM part fails, but in junkyard hunting make sure you test it within the warranty period.
I should add, one of the things I suggested that WM put in their controller was a test function that works before it's programmed, and they took the suggestion. So you can check the PWM circuit on any fan you buy by hooking the fan and controller up to 12V and throwing the test switch.

PATHFINDER99NI
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Vstar-
I was looking at Flex-a-Lites website and came a cross this:
https://flex-a-lite.com/electric-fans/1 ... -wave.html
I was looking at their 16" puller. At 3000cfm, would that be too much for the Pathfinder? It looks like these are brushless too.

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VStar650CL
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The vid shows it's 2-wire, so it might be brushless internally, but there's no PWM wire and that means the speed won't be controllable. The reason certain ones aren't reversible is the blades and not the motor, the non-reversible ones have a wing-shaped blade cross section that would be seriously compromised by spinning it backwards. They claim the 16-inchers are good to about 4L displacement, which sounds about right. They're about 280 watts which is small compared to most BLDC's (most run 400W plus), but the efficient blade design should somewhat make up for the lower speed and power.

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VStar650CL wrote:
Thu Aug 25, 2022 6:02 pm
The vid shows it's 2-wire, so it might be brushless internally, but there's no PWM wire and that means the speed won't be controllable. The reason certain ones aren't reversible is the blades and not the motor, the non-reversible ones have a wing-shaped blade cross section that would be seriously compromised by spinning it backwards. They claim the 16-inchers are good to about 4L displacement, which sounds about right. They're about 280 watts which is small compared to most BLDC's (most run 400W plus), but the efficient blade design should somewhat make up for the lower speed and power.
You are correct, I didnt notice that. Ive reached out to Spal to see what they have in the way of brushless. Ill report back whatever I find.

PATHFINDER99NI
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VStar650CL wrote:
Sun Aug 14, 2022 7:06 am
PATHFINDER99NI wrote:
Sun Aug 14, 2022 6:17 am
I’ll keep an eye out for that four pin connector.
Three or four. The key is the wire sizes, two fat and one or two skinny is what you're looking for. If you get the VIN off the JY donor before you actually buy it, I can look the car up in Identifix for you and confirm whether it's PWM.
Vstar,
Im finally getting to installing the fans. I went to the junkyard and picked up some fans from a '01 Altima. They fit the width (28"), but are just short on height (16.25" vs 19 .75"), but the fans are 12.5". I got the idea from this video https://www.youtube.com/watch?v=ZDibzo2SWwc&t=433s The guy in this video said they worked great and kept the heat down, so I think Ill be ok. He uses a Hayden 3647 harness, but that only does one speed. What do you think of this setup? Id rather go with a harness that uses both high and low speeds.

I did notice that each fan has four wires, three large gauge and one smaller gauge, does this make the fans PWM? If they are, can I use a simple harness to control them, and then add your PWM controller at a later date? I prefer that route, but Im in a time pinch at the moment. The part number of the fan is 21481-07000. https://www.nissanpartsdeal.com/parts/n ... 0z000.html

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VStar650CL
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The Altima fans definitely aren't PWM, they're dual-winding and Nissan uses three relays to drive them at low and high speeds. See EC-436 here for the factory wiring scheme:
https://www.nicoclub.com/service-manual ... 1%2Fec.pdf

Frankly, if those fans fit well in hole then you might try a set of '16~'19 Chevy Volt fans. They're true PWM duals (SPAL) with a profile of 28x16.5" and they move a crap-ton of air.

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VStar650CL wrote:
Thu Aug 17, 2023 12:50 pm
The Altima fans definitely aren't PWM, they're dual-winding and Nissan uses three relays to drive them at low and high speeds. See EC-436 here for the factory wiring scheme:
https://www.nicoclub.com/service-manual ... 1%2Fec.pdf

Frankly, if those fans fit well in hole then you might try a set of '16~'19 Chevy Volt fans. They're true PWM duals (SPAL) with a profile of 28x16.5" and they move a crap-ton of air.
Ok, PWM isn't needed at this point, for now I just need a set of fans that work. In your opinion, do I really need a high and low speeds? I do plan on splicing into the AC compressor wire to get the signal for the fans to turn on with the AC. I dont like the idea of putting a probe into the radiator, seems like a problem waiting to happen. Can I just cut the probe off and splice it into the temp sensor? How about the fans running after the truck has been parked, do you think this is necessary?

When I decide to go the PWM route, Ill give those fans a go along with your PWM controller.

Thanks again for your assistance.

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VStar650CL
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You should be fine just running both fans on high, it will be noisy as hell but should work fine. I'm always leery of radiator probes simply because a bad 'stat will make the radiator go cold and you'll lose airflow just when you need it most. However, the existing temp sensor is a sensor, not a switch. You can't use it directly for fan control. Since most Nissans don't have any spare ports into the cylinder head or 'stat housing, your best option for on-off control is probably a switch installed in an inline fitting on one of the smaller hoses from the coolant manifold, i.e., oil cooler, throttle body, etc. On a VG there's usually also a bleed port in the intake manifold, you might be able to find a switch with the right threads for that.

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VStar650CL wrote:
Thu Aug 17, 2023 1:53 pm
You should be fine just running both fans on high, it will be noisy as hell but should work fine. I'm always leery of radiator probes simply because a bad 'stat will make the radiator go cold and you'll lose airflow just when you need it most. However, the existing temp sensor is a sensor, not a switch. You can't use it directly for fan control. Since most Nissans don't have any spare ports into the cylinder head or 'stat housing, your best option for on-off control is probably a switch installed in an inline fitting on one of the smaller hoses from the coolant manifold, i.e., oil cooler, throttle body, etc. On a VG there's usually also a bleed port in the intake manifold, you might be able to find a switch with the right threads for that.
Ahhh yes, you are correct. I don't know what I was thinking, thanks for the clarification.

I did go look at the sensor and there is a boss just behind where the sensor is. I guess all I have to do is drill and tap that and I have a spot for the switch.
So when the switch comes up to temperature, its supposed to run both fans on low correct? And then when the AC is turned on, its supposed to switch to high? Is this correct?

I'm looking at this harness, what do you think? https://bp-automotive.com/product/dual- ... relay-kit/
Last edited by PATHFINDER99NI on Thu Aug 17, 2023 2:59 pm, edited 1 time in total.

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VStar650CL
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You're not going to make that work right without some sort of controller. They should come on low or high depending on engine temperature and A/C pressure. The only "fixed" factor is that they should at least come on low with the A/C compressor. The only "dumb" way to do it is to use a pair of relays with one hooked to the A/C compressor and driving the L+ terminals on the fans and the other hooked to the ECT switch and driving the H+ terminals. Very stilted and a whole lot of wiring. My advice is, you're going to cause more problems than you cure by looking for easy outs. Get a controller and adapt the harness and temp sender. Or get a set of Volt fans and a WM controller, you'll be up in one afternoon using the existing ECT with no drilling and no wire monster.

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VStar650CL wrote:
Thu Aug 17, 2023 2:52 pm
You're not going to make that work right without some sort of controller. They should come on low or high depending on engine temperature and A/C pressure. The only "fixed" factor is that they should at least come on low with the A/C compressor. The only "dumb" way to do it is to use a pair of relays with one hooked to the A/C compressor and driving the L+ terminals on the fans and the other hooked to the ECT switch and driving the H+ terminals. Very stilted and a whole lot of wiring. My advice is, you're going to cause more problems than you cure by looking for easy outs. Get a controller and adapt the harness and temp sender. Or get a set of Volt fans and a WM controller, you'll be up in one afternoon using the existing ECT with no drilling and no wire monster.
What controller do you recommend? I know you recommended your PWM controller earlier in this thread, but since these aren't PWM fans I'll need a different controller, right? So with this controller, I will also need a relay harness, correct? Will this one work? https://bp-automotive.com/product/dual- ... relay-kit/

I need to know the amp drawing of these fans, where can I find that info?

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VStar650CL
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That's just a relay kit, you can use it to drive the fans but it will only do one speed and it doesn't have any temperature switch. The way they suggest to use it for two fans is foolish, running one fan at a time causes parasitic circulation through the fan that's turned off. Something like this will work, but you'll still need to add a temperature switch, then arrange a control relay to trigger the low speed fan relays with the A/C, then another control relay to trigger the high speed from the temp switch, plus a cutout relay to let the temp relay override the A/C relay:
https://bp-automotive.com/product/dual- ... relay-kit/

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VStar650CL wrote:
Thu Aug 17, 2023 5:33 pm
That's just a relay kit, you can use it to drive the fans but it will only do one speed and it doesn't have any temperature switch. The way they suggest to use it for two fans is foolish, running one fan at a time causes parasitic circulation through the fan that's turned off. Something like this will work, but you'll still need to add a temperature switch, then arrange a control relay to trigger the low speed fan relays with the A/C, then another control relay to trigger the high speed from the temp switch, plus a cutout relay to let the temp relay override the A/C relay:
https://bp-automotive.com/product/dual- ... relay-kit/
So would I use this controller in conjunction with the BP automotive relay kit? The BP kit says its rated for 30a. Do you think thats sufficient for these fans?

https://www.summitracing.com/parts/dcw- ... 1rEALw_wcB

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VStar650CL
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That one will do the job by itself, without the BP. The relays are staged with a 10 second delay to reduce the startup load, and it does have an A/C override. You should get their threaded adaptor and make a port for the sensor. That all said, the fans will still only operate at one speed, on or off. There's no provision for two speed operation.

Mike W.
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VStar650CL wrote:
Fri Aug 18, 2023 3:14 pm
That all said, the fans will still only operate at one speed, on or off. There's no provision for two speed operation.
Ok, I'm a car snob, I admit it. But I hear cheap crapboxes with electric fans cycling between sounding like a 747 getting ready for take off, and silence, and I cringe and give praise it's not my vehicle. I don't demand total silence, but the contrast between WRRRRRRRR, then ..........., then back to WRRRRRRR just drives me nuts.

PWM fans are obviously a more modern and when done well, better solution, but I'm happy with what I did, which uses a simple resistor in line for low speed, with the A/C compressor, and direct for high speed. Now I did just use it as an Aux fan, not as a substitute for the main, but the fan I used came with a resistor on the frame, but even if it didn't, Amazon has plenty of high capacity ones for cheap. I used compressor signal for low speed, and one of those crappy stick it in the radiator fins controllers for high speed. Kind of winged it for the setpoint, a little over half and a little above where it would come one idling in the garage, in warm weather with the A/C on. I never hear it unless I'm outside the truck, and barely then, and the temp gauge never moves above halfway.

I see I omitted the fan controller/switch, but it's pretty basic, 2 wires. I also in retrospect probably should have switched ground, not hot, but no biggie. The resistor is not visible in my diagram, but is simply in line in the yellow low speed wire. Link to thread, topic616904.html

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VStar650CL
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Mike W. wrote:
Sat Aug 19, 2023 11:32 pm
Ok, I'm a car snob, I admit it. But I hear cheap crapboxes with electric fans cycling between sounding like a 747 getting ready for take off, and silence, and I cringe and give praise it's not my vehicle. I don't demand total silence, but the contrast between WRRRRRRRR, then ..........., then back to WRRRRRRR just drives me nuts.

PWM fans are obviously a more modern and when done well, better solution, but I'm happy with what I did, which uses a simple resistor in line for low speed, with the A/C compressor, and direct for high speed. Now I did just use it as an Aux fan, not as a substitute for the main, but the fan I used came with a resistor on the frame, but even if it didn't, Amazon has plenty of high capacity ones for cheap. I used compressor signal for low speed, and one of those crappy stick it in the radiator fins controllers for high speed. Kind of winged it for the setpoint, a little over half and a little above where it would come one idling in the garage, in warm weather with the A/C on. I never hear it unless I'm outside the truck, and barely then, and the temp gauge never moves above halfway.

I see I omitted the fan controller/switch, but it's pretty basic, 2 wires. I also in retrospect probably should have switched ground, not hot, but no biggie. The resistor is not visible in my diagram, but is simply in line in the yellow low speed wire.
You can also put the two fans in series to get half speed and parallel for full speed, that's how most OEM's do it. Nissan does it on their 3-speed setups, the "low" setting hooks both of the L windings in series, medium puts them in parallel, and high kicks in the H windings. There are lots of ways to get different speeds. The problem when using the fans as primary and not auxiliary is always the control side, i.e., how to govern when the fans run high and when they run low. That's handled by the ECM in OE setups, but trying to duplicate it with switches and relays is, um... let's just say, not optimal. Most guys end up with either an unreliable wire monster or settling for WRRRRRRR.

To my thinking, it's all pointless. Brushless fans used to be $600 items even from a junkyard, and then nobody made affordable controllers. Nowadays you can get a brand new Dorman clone of the Volt fans for under $200 or an 850W ZL1 monster for under $400. Ford Fusion fans are a dime a dozen and work fine with PWM even though they're "faux brushless", a brushed fan with a Solid State Relay controller. So if you're going to go through the trouble of modifying or fabricating shrouds, tearing out mechanicals, and routing wires, IMHO you might as well do it right. It doesn't cost a whole lot extra and you won't be settling for WRRRRRR.


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