Cooling Fan Query

So, heres the skinny. Just installed my EDP turbo on my 2014 GT A6. The kit came with a slim dual fan setup from Jegs.

The fan came to me, already wired to the output of the resistor. Both fans are paralleled.

While data logging, I noticed that the temps were getting higher than I liked. After some observation, the fans were only coming on after 210 ECT or the A/C was on. I verified with my tuner that the low speed is triggers at 185 in the tune. ( Swapped the HS & LS relay, to verify both were operable )

What this boils down to it that the low speed resistor has failed, MAYBE because of the load of two fans instead of the one OEM unit.

My question: There is a 40A max fuse for the cooling fans. There is a high speed relay and a low speed relay. At the resistor, there is a ground, and two 12V+ feeds, one is HS, the other is LS.

If I remove the resistor from the picture, parallel the grounds for the fans, hook the 12V+ from one fan to the LS and the other fan to the HS..... when the HS fan is on, will the LS wire still be energized?

The ultimate goal is to have the PCM control the fans. One fan on for LS and the second comes on for HS.

I guess the last option would be some crazy ass bundle of relays and diodes. In that case, I welcome any of you to offer a schematic of how that would work.

So what you are asking is if the two parallel fans can be staged independently using the low and high speed relays.

First and foremost I would contact Jegs and ask WTF? IT's their "plug-n-play" kit have them work with you on it. Always best to go to the source rather than a third party source.

That said in the event they blow you off:


That depends on the current draw of the two fans added together. Current is additive in parallel. If the two fans being fed by the same 40 amp fuse (F7) draw more than 20 amps each the fuse will blow. Here again Jegs would know the max current rating on these fans at full tilt. To go further on this, a 40 amp circuit cannot be run at 40amps. It will blow the fuse. Most engineers factor fusing at 120-150% oft he circuit load. Meaning that on a 40 amp fused circuit calculated maximum average current will be 20-30 amps. Therefore your fans should be rated at 10-15amps maximum current draw each (total 20-30amps) for the circuit to operate safely and no overcome the fuse.

An alternative way to get around this would be to add two 30 amp in line fuses and two additional relays from the BEC main 12vdc bus. They will be triggered by the low and high speed relay. Each fuse and relay will control one fan. You can low stage one fan at one temp and bring the second fan on at a higher temp stage level.

The green /white stripe wire coming from the lowspeed relay would be tied directly to one relay coil and the brown wire coming from the high speed relay would control the other relay coil. Then its simply a matter of pulling a fused 30 amp service wire to the relay contact and then tie each side into its specific fan motor. Obviously the other side of the cooling fans could and would share a common ground point.

Personally I would kick both fans on at 195-ish and add the 170 degree T-stat if you haven't already. My setup runs 199 normal with the 170 T-stat and tune correction to accommodate and will get upwards of 215 on a hard pull on a quarter mile pass. Engine temps with FI are going to be higher obviously. Don't get concerned with 210-215 engine temps. The Coyote was designed to operate at a higher engine temp to reduce emissions. The days of 160-180 on normal engine temps is a thing of the past for the most part.

Hope this helps