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onespiritbrain

Electric Radiator Fan Relay Help

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I am trying to figure out how to set up relays for controlling an electric radiator fan. I have it hooked up now and it works very well but it will run after the engine is shut off. I have spent literally hours trying to figure out how to set these relays up...

 

 

 

Can someone who understands this stuff please look over what I have so far and tell me if its going to work correctly?

 

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The only issues I can see for myself are:

 

1. Turning the AC on will kick the fan out of high speed unless I manually activate the recirc switch (which is always off by default..)

 

 2. If I turn recirc on without the AC on and the fan is running on low then both low and high motor leads will be energized. I don’t know what will happen to the motor if this occurs.

 

As I was typing the third issue I noticed what I thought may be an issue could actually solve the first issue IF the dual temp switch connects both grounds inside itself when its high temp setting is reached. Then even if I have the AC on but recirc off and it reaches its high temp setting it will pass the ground through itself and activate the fans high speed.

 

 

 

If the dual temp switch doesnt connect both grounds, is there any way I can have the fan run on high speed if the high temp set point is met?

 

Here is a drawing from the tech library at therangerstation.com of the Volvo relay:

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Here are some pics from the install:

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I am not familiar with the Volvo fan relay, so unfortunately I don't think I can really help too much with your electrical issues. However, I am curious as to what you are trying to achieve by installing an electric cooling system fan that reduces the radiator efficiency by 20% (due to some of it not being shrouded).

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Reduced area much be outweighed by increasing flow. During hot and humid summer days in Georgia my cooling system can’t keep up driving off-road, on long steep grades, in long drive thru lines, extended periods in parking lots, etc.

Also when stopping at red lights, or any of the above mentioned situations, the AC starts blowing warmer air. The electric fan pulls so much more air that the AC condenser even has air flow.

I had this exact same problem with my 2001 Frontier and I replaced the radiator and fan clutch on it. I’ve replaced my thermal fan clutch and radiator on my QX4 but as before the issue, while not as bad, is still there.

It’s like the factory cooling system is just barely enough to do its job and any sort of added heat load (including the AC) or reduced capacity (radiator scaling?) results in a situation where the engine temp rises slowly but indefinitely..

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I'm replying on my phone so I can't see your post to refer to.

Your wiring diagram isn't complete b/c relay 1&2 wouldn't work without other wires.

Relay 2 shouldn't be N/C, it should be N/O, closes ground when power is applied from the ignition, and I think it will never come on for temp wired that way. It would come on for AC and recirc, since I think those bypassed it.

I don't see why you have relay 1 and 2, that should require only one relay.

Why did you choose to switch the ground to the sensor to disable the fan with the engine off? The Ranger station schematic shows cutting the switched +. Was it to avoid circuit ringing if cutting power with the fan on?

Why are you turning on the fan when recirc is on? I have a 1 speed fan and it comes on full power when I turn on AC, recirc setting isn't involved.

I love my electric radiator fan. I used a Flex-a-lite black magic extreme. It has the same problem of not covering 20% of the radiator. But even in Dallas heat the AC is cooler when stopped, the engine heat is well controlled (I have a ScanGauge II), the engine runs smoother, and seems to be a little peppier.

Sent from my SM-N950U using Tapatalk

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This is with the rest of the wires shown
9915a82f5129ba20de0be1ad9ec6b5a3.jpg
By feeding the coil ground on relay #3 from NO on relay #2 it will eliminate the issue of having the recirc button on with no AC running

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here is the circuit and it looks like it does indeed work!!! 

 

http://tinyurl.com/y46lm8gc

 

I want to figure out a way where the dual temp switch cannot be overridden IF the coolant is at 99degC or above. 

 

I dont see a way to eliminate the ground break relay. How can I eliminate it?

I am switching the ground because its milliamps instead of fla for the fan. 

 

Im probably just going to tell the fan to kick on high with the AC clutch instead of trying to get crazy with the recirc thing.. its going to be a pain in the arse to run wires to that plug anyway and im not going to want to have to hit the recirc button all the time when the ac isnt cold enough..

Edited by onespiritbrain

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I went with the last design and it’s working. I am very happy with the improved air conditioner performance.

 

I do have to say that with the AC on full blast and the fan on high speed, it seems like I actually have less power than before. It’s not much so it might just be me but I can’t discern any extra power whatsoever.

 

I wonder if the increased power draw on the alternator is causing a noticeable increase in mechanical resistance.

 

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I went with the last design and it’s working. I am very happy with the improved air conditioner performance.
 
I do have to say that with the AC on full blast and the fan on high speed, it seems like I actually have less power than before. It’s not much so it might just be me but I can’t discern any extra power whatsoever.
 
I wonder if the increased power draw on the alternator is causing a noticeable increase in mechanical resistance.
 
I imagine it is. I see the same thing when i turn on my headlights lol.

Sent from my SAMSUNG-SM-N920A using Tapatalk

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Yes, increased load on the electrical system puts more load on the engine. In the real world, there ain't no such thing as a free lunch. 

 

I converted to e-fans in my Pathfinder for several reasons, reduction in engine load was not one of them. One thing to note, the mechanical fan never achieved 100% lockup. The fan actually would slip more when the engine was under heavy load. You would have noticed a serious power loss and a lot of noise if the fan ever locked. Had that happen in my first car, my 1977 200SX when we were doing about 80 mph. Bearings failed in the fan clutch and it felt like we slammed into a foot deep puddle and a god awful howl came out of the engine bay. Drove it like that for about a year because at the time I could not afford to replace the operational water pump. I finally got tired of the noise and drag of that fan(my best friend lived a quarter mile away and could hear that thing if he was outside when I started the engine, and the local police told me they could hear it a half mile away when I was doing 40 mph) and converted to electric. All my cars since managed to lose the mechanical fan and go electric. I like the better temp control and extra room the electrics give me. 

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