Thread: Radiator fans different between AT and MT G20?

Hey folks. A while back I grabbed a radiator and fans from a G20 to upgrade my B13. I now see that the B13 fans were only two wires for both fans, wired in parallel, but the G20 fans are 4 wires each. And in going through the FSM for the '95 model, apparently the manual transmission wiring used two relays and a 30a fuse, but the automatic transmission version used three relays and two 30a fuses. I can only assume that this means that the AT version had beefier fans that drew more power.

Problem is, as I pulled this unit at the salvage yard, I didn't pay attention to what it came from, so I'm not sure which version I have. Is there any easy way to tell? Or did Infiniti just split the circuit to play it safe, and the fans are actually the same?

Since there are two speed settings, I'd like to take advantage of that, but wiring this up may be more of a hassle than it's worth.

With 4 wires there you should have 3 speed fans.
You can wire to either input and run them as single speed fans if you want.

Two of the wires are grounds, speeds are High/Low/Off. Relevant schematics attached. What I can't determine from the FSM is if the signal to turn the fans on at low speed (Relay 1) remains on when the fans go to high speed, or if the low speed signal drops and only the high speed setting remains.

B13 mt are single speed 2-wire fans. B13 auto are dual speed 4-wire fans. To get high speed both circuits of each fan have to be powered. Powering only one circuit (doesn't matter which one ) gives you low speed. Same setup with Maxima fans 88-94.

Doh... I should think and focus before typing away.
I can't remember if the low speed ECM output toggles off during hi speed operation. I have my L30 altima here at the shop, and it is a slow day. I may be able to check this with Consult if time allows.

Well, like I said, these were out of a G20. I think it was a '95, but may have been a '99, no later. At this point I have no recollection on which transmission that car had. Wiring for the B13 is irrelevant at this point.

I'm thinking that I may need to err on the side of caution and wire them up according to the Auto Tranny schematic. I'll need to add two more relays (I've got a few empty relay spots, and can always rip out ones I'm not using) and can repurpose a fuse to get the extra 30a circuit. The B13 SE-R never came with power windows, but yet there is a power window 30A fuse installed.

My meter at home can only measure up to 10a, I checked both fans on low, one was about 5.5a, the other about 7a. I know the high speed setting will draw more power, but it seems a safe bet that this will be more than 10a, so I can't easily measure that, but I'm assuming twice the current draw. So I could have two fans pulling anywhere from 20-25a on high, or somewhere in the 30-35a range. Wiring each to a 30a fuse seems a safe move to avoid problems.

Or I could simplify things and wire them up for high speed only. I'd really have no way to run them as dual speed without adding a switch to activate the different speed, and the car will mainly be used at the track, so more air would be helpful. I have to assume that the original B13 fans were running faster than the low speed setting on the G20 fans anyway.





If you can possibly confirm that, it would be helpful!

Jim, the L30 shuts off the fan low output when switching on the fan hi output.
The fan logic should be the same with your setup.

Excellent. Worst case I try that and the fan doesn't spin any faster with these. I've got an ammeter ordered that will let me check current up to 100a, so I should be able to get good numbers once this comes in.

Appreciate the help!

Did some testing tonight, figured out how to tell the difference. I didn't read that wiring diagram closely enough. For the automatic transmission version with three relays, pin 1 on the fans are slightly different, one is Brown, one is Brown White. The 2 relay Manual Transmission fans are both Brown. Also, for anyone that tries to check this themselves, this is not the wire that is on the fan itself, the fan wires go to a 4 pin connector, one of these connectors will have a Brown wire, the other will have Brown/White. At this point I can't remember which fan would have the Br/W wire.

There is a small difference in fan speed and amperage as well. What I'm seeing may well be because of the age of the fans no longer operating at 100% efficiency.

Low speed runs around 5-6 amps, high speed runs around 8-9 amps. Surge current when the fans first spin up is a few amps higher.

I think that my plan is definitely to run these at high speed only, so that means I can ground the red and black wires (black are always grounded, high speed red ground is switched in, so eliminating that means I can leave those grounded), and so all I have to run through the relay are the Brown and Br/White wires. I snagged a 30a 2-pole relay (Brown in color) and matching holder at the junk yard this weekend, I'll be working to splice that in this week.

I think @MudPuppy could use this info...or coulda