Amp draw of 3 fan configuration?

[mkassab]

For those with a 3 fan cooling configuration (i.e., 2 pushers and 1 pull)... what's the total amp draw? I'm trying to determine if I need two circuits or would one 30/40 amp relay circuit do?

Thanks Mark

[RJacobsen]

Mark, I have a dual spal fan setup on my car and the wiring diagram that came with it required a separate relay for each fan. Not sure if that is realy nessasary but that what they recomended.

[Jim Harding]

Mark, I have the two pushers in front and a single puller behind the radiator. I run them on seperate relays and dash switches. Also the puller has a thermostat in the intake manifold to turn on the fan when things get over 180 degrees..... should I forget to turn on the switch...... which has happened a few times before I put it in. I never measured the actual current flow in either fan, but I use a 30 Amp circuit breaker rather than a fuse, and number 10 gauge wire to the puller. The pusher fans, IMHO, are more for show than cooling. The puller does the job and temps never go much over 200 on the hottest days or while stopped in traffic.

- Jim -

[mkassab]

Jim…. 100% concur with you. I thinking along the same lines except with a few twists. Copied from my Eng/Cooling build thread.... I’ll have one master fan switch for all 3 fans that will provide power to two relays. I’ll always leave the power switch on (normal position) unless I need to turn them off for some reason. The rear fan will be controlled by a variable speed and temp controller, see link and description below. The rear fan will start at low speed at 180degs. The front fans will kick in at 200degs (off at 180 degs).

Side note: I actually will have 3 switches that on in the normal on position (i.e., Fan, AccuSump and fuel pump). These three switches will have a flip-up safety cover, the switches will be turned upside down so when ON the switch lever is down, in the on position, and the cover closed. You can see more details (electric diagram, dash layout, etc) on “Mark’s Build” forum @ http://www.uniquecobra.com/forums/forumdisplay.php?f=68

Variable Speed & Temp Fan Controller:
http://www.summitracing.com/parts/FLX-31163/

Flex-a-lite variable speed controllers attach on or near the electric fan, sensing coolant temperature via a temperature sending unit. I’ll set fan speed from 60 to 100 percent, depending on the built-in thermostat's setting. The thermostats have a range of 160-220 degrees F. The variable speed controllers allow greater control over engine temperature, which helps to reduce charging spikes and current load on the charging system. It allow a maximum load of 30 amps, and keep the fans running for 30 seconds after your vehicle is turned off.

[pgermond]

I try to keep it simple (this isn't a rocket science) - two pushers, one puller, on relay, one switch, one 20 amp fuse.