EFK wiring: I didn't want the fan to ALWAYS run with A/C so I did this.

[Angular]

So there are probably a dozen threads on AZ alone about how to wire up your electric fan kit, but I haven't seen anyone take this approach. As you guys know the common way to wire up the EFK relay (per JHM, et al) is to tap the brown & green wire (pin 7) on the 14 point connector near the driver's side headlamp. Looking at the wiring diagram you'd think this would activate the fan when the lower radiator hose temp switch kicks in. However from what I've read and experienced myself, the EFK fan winds up coming on with the A/C regardless of coolant temperature which is pretty lame.

Frankly, I was baffled as to how this is possible. One side of the relay coil goes to +12V and the other side typically must be connected to ground to complete the circuit and activate the relay. Knowing that the coolant temp switch (F18 in the wiring diagram) was open, the only explanation is that the fan control module (FCM) or possibly the A/C control module was sinking enough current to turn relay on. Wacky sh!t. I don't know if that's a bug or a "feature" but I didn't like it.

The apparent solution was to install a diode in that brown/green wire between the FCM and the tap for the EFK relay. This stopped the EFK fan from coming on with the A/C. I simulated the coolant temp switch activating by jumpering that wire to ground and sure enough (when the engine is running) the aux fans come on at low speed. Wanted to make sure the diode didn't interfere with the FCM and A/C controller getting the right "signal". Seems to work exactly as desired.

Here's a picture of where I put the diode and the wiring diagram from the Bentley manual that I marked up with where the diode goes (note the green circle).

[NOTORIOUS VR]

That's all fine and dandy Brad, but when you're in stop and go traffic with the AC on, you will want to have it on all the time when the AC is on. So then what? :P

[getslideways]

Kudos on figuring out a way ot get it to operate to your liking.

However, its supposed to operate that way (coming on with the A/C) because an A/C system needs airflow over the condenser for it to work properly. As pointed out above, the mechanical fan, or 3rd front fan used to preform this task while stationary or at low speed, but since those are now gone, the EFK must compensate for their departure. That's why pop machines, refrigerators, etc all have little fans in them to move air across their condenser. I think you may want to reconsider this unless you are removing your A/C system completely. You can always press the "econ" button to turn off the fan and A/C system while operating the climate control.

[hibiscusS4]

someone cut the fog lights outta my car so im just gonna wire my efk to the fog switch and bam in cabin button lmfao.

[2000s4_m]

What i did was to run a flex-a-lite variable speed fan controller, is is very capable and can support both fans, the way that works is that if you turn your ac on the controller run the fans at 50% and if your engine ever gets any hotter it starts upgrading that fan speed gradually until it cools down and then starts to gradually slow the fan speed to 50% or less if you have your ac off, i think system is very capable because i rarely hear the fans raise the speed and i live in texas so heat is very present!!!


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[Angular]

That's all fine and dandy Brad, but when you're in stop and go traffic with the AC on, you will want to have it on all the time when the AC is on. So then what? :P

Never happens. However, when/if I move to Hawaii I will probably consider rewiring the stupid fan.

However, its supposed to operate that way (coming on with the A/C) because an A/C system needs airflow over the condenser for it to work properly. As pointed out above, the mechanical fan, or 3rd front fan used to preform this task while stationary or at low speed, but since those are now gone, the EFK must compensate for their departure. That's why pop machines, refrigerators, etc all have little fans in them to move air across their condenser. I think you may want to reconsider this unless you are removing your A/C system completely. You can always press the "econ" button to turn off the fan and A/C system while operating the climate control.

I understand how refrigeration systems work and certainly this isn't the mod for people that live in a warm climate or need max A/C efficiency in stop & go traffic. But for someone like me that lives in a cooler climate this was a simple and effective solution to a noisy fan that was running almost 100% of the time when it didn't need to. Let's not forget the two auxiliary cooling fans still run whenever the A/C is on so there always some airflow over the condenser even at a stop. Incidentally, I almost never use "ECON" mode because the A/C is still necessary to dehumidify the air when the heat is on.

So, yeah, this is far from the optimal solution for quiet AND efficient electric radiator fan operation in all climates. Better solutions would include a two-speed fan and/or a thermostat-relay combo unit with a temp sensor probe to turn the fan on/off.

[Angular]

What i did was to run a flex-a-lite variable speed fan controller, is is very capable and can support both fans, the way that works is that if you turn your ac on the controller run the fans at 50% and if your engine ever gets any hotter it starts upgrading that fan speed gradually until it cools down and then starts to gradually slow the fan speed to 50% or less if you have your ac off, i think system is very capable because i rarely hear the fans raise the speed and i live in texas so heat is very present!!!

Nice. If I ever move to a warmer climate, I'll probably do the same!

[getslideways]

Never happens. However, when/if I move to Hawaii I will probably consider rewiring the stupid fan.

you must tell me your secret to avoiding traffic on 167, I-5, 18, and 405 when trying to escape the 253. Is there a secret club I need to join? Will you vouch for me as a member?

I understand how refrigeration systems work and certainly this isn't the mod for people that live in a warm climate or need max A/C efficiency in stop & go traffic. But for someone like me that lives in a cooler climate this was a simple and effective solution to a noisy fan that was running almost 100% of the time when it didn't need to. Let's not forget the two auxiliary cooling fans still run whenever the A/C is on so there always some airflow over the condenser even at a stop. Incidentally, I almost never use "ECON" mode because the A/C is still necessary to dehumidify the air when the heat is on.

So, yeah, this is far from the optimal solution for quiet AND efficient electric radiator fan operation in all climates. Better solutions would include a two-speed fan and/or a thermostat-relay combo unit with a temp sensor probe to turn the fan on/off.

Seattle's past summer wasn't exactly chilly, especially when you put some distance between yourself and the sound/lake. However perhaps spending some time in beautiful HI makes a warm Seattle summer not seem quite so warm in comparison.

Do you still have your 3rd fan in front of the radiator? If so, then yes, having your EFK pop on with the A/C system would be redundant. That fan is usually deleted with an EFK install. You are also right about the little guy on the passenger side coming on with the A/C, and yes, A/C isn't just for making air cold, contrary to popular belief. Hence why pushing the dedicated front windshield defroster button on the climate control automatically turns off econ mode as well.

Did you go with a straight blade fan or an "s" blade? I ran an "S" for my EFK setup as I was concerned about noise too, and its barely noticeable with the car running and me standing outside of it.

As long as you are happy, and its functioning the way you like, then that's all the matters.

[Eurotuned_A4]

No no no, if you move to Hawaii you will sell me your car!! You cant take that beautiful thing to get eaten by saltwater and sand! To compensate I would let you take my none widebody casablanca avant lol. BTW, it was nice meeting you at AMDs BBQ!

[Angular]

you must tell me your secret to avoiding traffic on 167, I-5, 18, and 405 when trying to escape the 253. Is there a secret club I need to join? Will you vouch for me as a member?

Easy... live in Federal Way, work in Tacoma, and stay the hell away from Seattle. When you must battle traffic, drive the wife's car.

Do you still have your 3rd fan in front of the radiator? If so, then yes, having your EFK pop on with the A/C system would be redundant. That fan is usually deleted with an EFK install.

Did you go with a straight blade fan or an "s" blade? I ran an "S" for my EFK setup as I was concerned about noise too, and its barely noticeable with the car running and me standing outside of it.

Yes, sir. I still have the 3rd fan in front. Unfortunately I got a straight blade SPAL fan from *cough* VAST *cough* and it's a bit noisy. Hindsight being 20/20, I wish I'd have ordered a dual speed S-blade fan of some kind.

[ravensB5S4]

Would there be a way of running two fan modules like newer audi's. One for the efk and another for the ac. I guess you might need to add code to the ecu, need to look at a newer audi wiring diagram, but dont have access. Probably not worth the effort.

[Angular]

No no no, if you move to Hawaii you will sell me your car!! You cant take that beautiful thing to get eaten by saltwater and sand! To compensate I would let you take my none widebody casablanca avant lol. BTW, it was nice meeting you at AMDs BBQ!

Dude, there's quite a list of people trying to get dibs on this thing if I ever do sell it! After 11+ years I think I'm a "lifer". Definitely not the ideal vehicle for the Kona lifestyle but it's hard to imagine parting with it... ESPECIALLY after having just dumped another big pile of money into it. On the plus side, should be pretty good/solid for the next 3-5 years or so with this latest refresh.

Would there be a way of running two fan modules like newer audi's. One for the efk and another for the ac. I guess you might need to add code to the ecu, need to look at a newer audi wiring diagram, but dont have access. Probably not worth the effort.

That's the thing... finding a solution that's cost effective, not too complex or difficult to implement, and gets the job done. A dual speed fan or a variable speed fan controller like the guy from Texas is using are pretty good options.

Out of curiosity when I got home tonight I turned off the A/C and let the car idle until the coolant temp switch (F18, located in the lower radiator hose) kicked the fan on. Never did the needle on the coolant temp gauge inside the car exceed the straight-up middle position and the A/C condenser remained cool to the touch. Turning off the A/C was essential because the two aux fans alone are enough to keep things cool at idle with ambient temps around 50 F.

[topquarkpc]

thumbs up for local dude figuring things out...
must've missed AMD GTG...would've been nice to meet some local folks...
btw...your vaca rental home looks familiar... were you ever on a reality show "buy Hawaii"? just wondering...
also sent you a pm...

[Uber]

What are the specs on the diode you used?

[Angular]

What are the specs on the diode you used?

It's just a common 1 amp "rectifier diode", part # 1N4001 or similar. Cheap, easy to find, reasonably durable for this application.

[ilyafil]

I wired mine to the fan plug for the fan in front of the condenser. It works great.

[Uber]

It's just a common 1 amp "rectifier diode", part # 1N4001 or similar. Cheap, easy to find, reasonably durable for this application.

Thanks

[bmos]

I wired mine to the fan plug for the fan in front of the condenser. It works great.

Didn't you read the thread first post? The whole point is to make the fan not always turn on with the secondary fan...