electric fan thermostat switch question

[buzz77]

New question. What is the benefit of having dual relays and fuses for dual fans when many of this single relay kits can animate a 2 fan set up. I'm looking at doing a simple set up, so the less the wiring the better.

 

[darbysan]

Depending on how you set them up, dual fans can run either independently or together, or at low speed or high speed. Either of these conditions require two relays minimum ( mine uses 3) to provide independent power to each fan. If you just want to turn them both on or off, one relay will work fine. I switched from a MarkVII fan to an LS1 fan setup so that I would have some redundancy. I had a MarkVII fan (single fan) go out on me, and struggled to get home. With the two fan setup, I will have at least one fan still operating if I lose one.

 

[84cutspreme]

The way mine work are pretty simple, and seems stupid to me. There is a 30amp relay for each fan and a relay for a/c. There is power from the battery direct to relay, an ignition run 12v, a ground aka sending unit and power to fan. the fan gets grounded separately. the way this setup works is that when sending unit reaches temperature it grounds and completes the circuit turning the fan on and shutting off when low temp is satisfied. The a/c relay uses the compressor power wire to trigger relay. When triggered the other side of relay runs to sending unit and grounds sending unit essentially tricking the fan relay to think it is at high temp to come on. The way the company had told me to install a toggle switch was just to run a ground from switch to sender so I'd be doing the same thing and grounding sender to trigger both fans to come on. I wanted to leave one fan hooked up to sender and a/c relay so it would operate normally, but I wanted to just control one fan and use a lighted toggle switch which wouldn't work just switching a ground. So I permanently grounded one of the fan relays and just put the switch in the ignition run 12v. So it works normally on/off and is independent of the 2nd fan. Only catch is if for some reason I am not paying attention and don't have fan switched on if the sender reaches high temp only the one fan will work...
That being said I want a controller which will automatically turn the both fans on at a low speed at adjusted temp to better maintain temp, and if needed if/when adjusted high temp is reached or a/c is turned on both fans will come on full in high speed. The main reason I would like this setup is because most of the companies use relays and a sender which works by letting the temperature rise to a predetermined setting to turn on and off. For example my sender choices were 185on/165off(which pretty much means once they come on they NEVER turn off), 195on/175off(which is my current setup with 180 t-stat), and lastly 210on/190off. The biggest thing to me is when I am idling the temp goes up and turns fans on high (btw nice 40amp draw), temp goes down and fans turn off...and repeat. I guess I'm just used to clutch fan that for the most part keeps a pretty consistent temp. So if I get a setup that maintains a average lower temp by running fans at low speed (aka less amp draw). I just really hate the hot/cold cycles having fans on/off/on/off
Plus I have nice semi-quiet s-blade fans but sitting idling at a light they both come on high pulling about 3600cfm that whirrrrinng noise gets on my nerves

 

[darbysan]

Here is the three-relay setup I use. Basically, if you run both fans in series, each fan will be running at 1/2 speed (low) (Relay 1 triggered via a ground signal). To go to high, relays 2 and 3 both get triggered. This breaks the serial connection of the motors, and supplies power to both fans ( high speed). I'm lucky enough to be able to use the ECM to control some of the temps, but you can easily do this without an ECM. Your engine temp switch can trigger the low speed circuit, and your AC or manual switch can trigger the high speed.

http://ls1tech.com/forums/conversions-hybrids/1155252-need-camaro-fan-motor-diagram.html

 

[buzz77]

Thanks that demystifies alot. One more question, who do some prefer a circuit breaker easyJet than a fuse?

 

[truracer20]

When a fuse blows it's done and you may not know there is an issue until the engine is overheated. A circuit breaker resets itself after an overload. So if there is an issue it won't get too far out of hand before it's noticed.