Auxiliary cooling fan issues

[pdrnec]

Hi y'all, it's been a while. I'm still wrangling the Stude herd, putting them back on the road one at a time. One of these days I'll get to one of those Fruas....

Today's project is trying to keep a 63 Cruiser with aftermarket AC cool in the SoCal heat. I put a dual pusher fan rig on it in front of the compressor and it is causing the ammeter to do whacky things.

I'm using a 50 amp Nippondenso alternator I got from Napa. When the fans kick in (they draw 15 amps combined) the ammeter goes to the charge side, about 3/4 way to max. At idle it is much less, as the motor revs higher it jumps up.

When I turn the headlights on, it drops down a touch. When the AC fans kick in, it drops down a touch more. Why does a 15 amp fan make the gauge go up when any other electrical device makes it go down?

[N8N]

Hey Pat, long time no see. I'm assuming that the fans are fed from a relay, and a thermoswitch and/or a switch on the dash and/or the A/C compressor clutch activate the relay. From where are you getting the main power feed for that relay? Also, is your alternator internally or externally regulated?

nate

[pdrnec]

Fans are relay fed, main power feed comes from the starter solenoid battery lead since it was right there. thermoswitch and the A/C compressor clutch activate the relay. Alternator is externally regulated - the Nippondenso is a drop in replacement for the OEM but puts out a little extra.

It's probably having a Honda part on it that's causing me problems, but neither Harley or Ducati makes anything that will fit.

[N8N]

I think that connection to the starter solenoid is your issue. because you're basically pulling the power from the big red wire coming from the ammeter, the total draw of the fans is counted in the charge current shown on the ammeter whenever the fans are drawing their power primarily from the alternator. When the fans are running off battery, then your ammeter would read zero (instead of -15A as it should be.) So if your ammeter is at 3/4 scale, it's a +/- 30A ammeter, that's about right (looks wrong, but does not seem to indicate a charging problem to me.) I would have recommended putting the relay on the pass. side fender and tapping directly off the back of the alternator; your ammeter would read correctly then. Basically you don't want to tap any power off the starter solenoid on an ammeter-equipped vehicle otherwise the ammeter readings get all funky. Alternately you could run a heavy wire from under the dash, tap the *other* side (black wire) of the ammeter, but then you'd probably want to use an inline fuse as that wire would then be more than a couple inches long. Or, finally, you could tap the black wire from the alternator to the ammeter as it runs along the fender. Please don't use a Scotch-Lok or a wire nut :P (I'm ASSuming that a '63 Cruiser still carries the wiring harness along the left fender and then across the front of the engine compartment to the alternator, like the other Studes I've worked on? Or does it go across the firewall like an Avanti? If the latter, forget the last suggestion.)

Much as I'd like to blame the Honda parts, I don't think that's the issue this time :/

nate

(now if the problem was, "my exhaust sounds like a flatulent bulldog" then yes, you could blame the Honda parts... <G>)

edit:

wiring diagram here, although I ASSume you already have it

http://www.studebakerparts.com/studebakerparts/store/s/html/images/63-4-lark-wire-COLOR.pdf

and thank you for making me think about this, I just realized exactly how I'm going to wire up the headlights on my '55, ASSuming that JDP hasn't thrown out the vintage headlight relay we scavenged from an Avanti.

[railway]

My electric fan when kicked on almost pegs the amp meter. have drove it a many miles that way, but scares me it might burn out. I think the fix is a voltage gauge. I'm tied to the red wire from the battery to the starter solenoid. This is on a 62 GT Hawk changed to alternator.

[pdrnec]

N8, you're a genius. I'll switch the feed wire to the ammeter tomorrow.

[N8N]

No, genius would be buying the rights to a product just before it goes huge :P I'm just good with electrons. (hey, it is what I think about most of the day.) I hope I'm right and that running a new wire "fixes" the "problem."

nate

[pdrnec]

Forgot to post the outcome - with the feed coming from the alternator the ammeter is dead center. I owe you several beers next time I make it to York.

[N8N]

sweet. so that means that a) I do occasionally know what I'm talking about and b) your alternator is keeping up with the load of the fans, both of which are good things to know

nate