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View Full Version : E-fan swap, switch idea



dp96zj
06-26-2010, 11:23 PM
I'm considering the e-fan swap (Texas summers with no a/c sucks), but don't really want to drop the coin on a controller. I'm fine with having to adjust the fan settings myself, so I'm probably just gonna do the relay->switch setup. My question is, instead of running a High/Low/Off switch, would it be possible to have a rotary knob type setup? Or maybe I could just find a switch with more increments (ex: 0% 25% 50% 75% and 100% power levels). I've been searching on here and google, and it looks like it might be possible. Any of you electrical guys wanna throw some knowledge at me?

96JGCL
06-27-2010, 12:41 AM
I'm considering the e-fan swap (Texas summers with no a/c sucks), but don't really want to drop the coin on a controller. I'm fine with having to adjust the fan settings myself, so I'm probably just gonna do the relay->switch setup. My question is, instead of running a High/Low/Off switch, would it be possible to have a rotary knob type setup? Or maybe I could just find a switch with more increments (ex: 0% 25% 50% 75% and 100% power levels). I've been searching on here and google, and it looks like it might be possible. Any of you electrical guys wanna throw some knowledge at me?

Think about this..

what other part of a vehicle has a fan and adjustable settings?

Blower motor

How you would do it, dunno Im one of those guys that gets the stuff, pulls it apart and figures out how to make it work along the way

SirFuego
06-27-2010, 12:59 AM
The best way is to find a schematic of the fan. If you can't find a schematic, you can probably take it apart and figure it out manually. Basically any IC is going to be labeled with a part number and any resistor/capacitor will be labeled such that you can determine its value. If you can't read schematics, post it up here and we could probably figure out what is going on.

Here is my guess as to what is going on. So please don't take this as being gospel since I've literally done zero research into the electronics...

The circuit is fundamentally going to be switch -- relays -- input electronics -- fan motor. Where the input electronics and fan motor are both physically part of the e-fan.

A 3-way switch like you described probably sends 12V to the appropriate setting on the input electronics. I very well could be wrong, but I'm going to guess that the input electronics consists of a multiplexer that sends different (hard-wired) voltage to the fan depending on the setting. If this is the case, you would need to bypass this circuit with a rotary switch since it will basically be a potentiometer that sends varying voltage to the fan -- which isn't the correct "type" of input.

So the rotary switch would require you to override the input electronics -- so then the question is how is the fan speed itself changed? If it varies by the voltage, the rotary switch might work if you can bypass the input electronics. That said, all switches and inputs need to be spec'd appropriately for the power requirements of the fan.

grandf4
06-27-2010, 01:45 AM
The real issue is that whatever switch/rotary unit you use would have to be capable of handling the current draw of the fan.....

Ken L
06-27-2010, 10:13 PM
The Taurus fan has 3 wires. One is ground, one is + for high speed and one is + for low.

Just my $0.02, but to make the fan infinitely variable may be more trouble than it's worth.

dp96zj
06-28-2010, 11:54 PM
Ok cool, thanks for the info guys. So pretty much, if I wanted to run a rotary knob, I'd be taking power wires into the cab-area, since the switch itself reads and supplies the correct voltage to the fan. I'll look into it a bit more, and see what I end up with!

albersondh
06-30-2010, 04:49 PM
I'm considering the e-fan swap (Texas summers with no a/c sucks), but don't really want to drop the coin on a controller. I'm fine with having to adjust the fan settings myself, so I'm probably just gonna do the relay->switch setup. My question is, instead of running a High/Low/Off switch, would it be possible to have a rotary knob type setup? Or maybe I could just find a switch with more increments (ex: 0% 25% 50% 75% and 100% power levels). I've been searching on here and google, and it looks like it might be possible. Any of you electrical guys wanna throw some knowledge at me?


I use 3 relays, one 80A continuous duty solenoid, and 2 cheap thermo-relays. About $100 in electronics. Low and high are indipendantly adjustable, as is the overlap from low to high. One of the relays kills the ground going to the relay that turns on/off the opposite speed relay. Its a redundant system where the low and high circuits operate independantly. When high comes on it kills the low side power, so your not constantly powering the low windings for no reason. If any part of the low circuit were to fail, it would just stay on high, if high failed, it would just stay on low.... You adjust low to slightly overlap the high-on setting. This way there is never a massive amp inrush through the circuit when high kicks in, since the fan is already spinning on the low setting..... Been running this sytem for years, not as cool as a full on controller but it gets the job the done and uses all the functionality of the fan. My pops is duplicating my system on his Benzo and I have to make him a shizmatic and a BOM, so that will be available if your interested....

albersondh
06-30-2010, 04:57 PM
Ok cool, thanks for the info guys. So pretty much, if I wanted to run a rotary knob, I'd be taking power wires into the cab-area, since the switch itself reads and supplies the correct voltage to the fan. I'll look into it a bit more, and see what I end up with!


You would want a rheostat. No pot will move enough current to make this work. The you would have to articulate the rheostat to match conditions.... Dont sound like fun to me.

See if you can find a simple motor controller that can move around 80 amps, then you could use a thermistor as your input to articulate speed controll.

Link to my fan wiring mess: http://www.mallcrawlin.com/forum/showthread.php?p=288306#post288306

dp96zj
07-20-2010, 11:14 AM
I've decided to go ahead and buy a controller (for simplicity's sake), and will most likely pick up the SPAL Fan Controller V3. The main reason that I'm going with this over the DCC box is because of the temp sensor. It picks up the reading from the stock (dash) coolant sensor, instead of having to stick a temp probe into the radiator. IMO I think it'd be a more solid design. That, along with their detailed instructions and somewhat less-expensive price tag make it look like a decent investment.

http://www.a1electric.com/Merchant2/merchant.mvc?Screen=PROD&Store_Code=AEOS&Product_Code=FAN-PWM-V3



I've read over the instructions posted on their website multiple times, and it looks like a pretty well-thought-out design. The only modification that I may do is to have a bypass switch so that I can either have the controller run the fan, or choose to run it myself with a hi/lo/off switch.

http://www.a1electric.com/spal/specs/FAN-PWM-V3.pdf




I'd probably spend that much on wiring, relays and rheostats alone, so the controller looks like a decent idea. Any objections or input?