Fan Install problems!! DOHC swap

[driftin_sr20det]

I've been doing a DOHC swap into my buddy's '90 coupe, and we've run into this issue with the electric fans I installed. We used 2-12" fans with a 40 amp relay. I first ran it from the fuel pump fuse to get a signal for the relay, when the fans were plugged in the motor would chug and die. Unplug the fans and it would idle perfect at 800. So I switched the signal wire over to the ACC from the fuse box on the driver side of the car, thinking that it was maybe pulling too much juice from the fuel pump circuit and causing it to run crappy. Well that also caused the same effect. So now I'm stuck wondering if its the battery, alternator, or something else. I searched and only found 3 situations close to mine and none of them had any difinative answer's. So any suggestions would be great.

[zerepdivad]

I went straight to my accessory wire in my ignition harness. I never had any problems. Do you have a multimeter? If so meter the voltage while the car is running without the fans and then meter it with and see if the voltage drops drastically. DId you ground the casing on the alternator as well? That could cause similar problems as well.

[-RJ-]

my friends 240 did the same thing. you can wire it up with a switch and wire it somewhere inside your car or you can wire it up to the cigarette lighter, this will mkae the fan turn on when you turn the iginition on

[driftin_sr20det]

You know that could be it, I'll check to make the alternator is grounded. Because that is what it acts like, like the battery is being drained and the alternator can't keep up. It even did it with one fan, not just with two... Sooo I'll start there... Open to more ideas! It will probably be about a week before we meet up and work on it again.

[bruinbear714]

Although the stock electrical system can support two fans constantly on, keeping them on constantly is a drain on your alternator.

If the engine is struggling, it might be an alternator issue or battery issue.

Do it right and get one of these DIF variable speed controller.

Keeping the fans on constantly is worse than using stock clutch fan due to the constant drain whereas the clutch fan only loads the engine as much as is required due to the built-in thermostat clutch.

[driftin_sr20det]

Appreciate that tip, but I really doubt my buddy is going to go for a $200 fan controller though. I do agree with the fact that running the fans continuously isn't the best idea. This is why I will be running mine off a thermostatic switch, which run around $25-$30. I'm going to see if I can't talk him into that. Basically now I'm sure its got to be the alternator or battery issue.

[LayNLow240]

They still have a 100$ fan controller for lower amperage and dual fan setup. Im trying to decide what i want to do.