[wave1957]

I am going to install an electric fan in my truck ('57 Chevy Suburban, 250ci inline 6 engine) and I am wondering what my options are to trigger the fan on and off: sensor in the head, sensor in the radiator, thing that measure the air temperature after the rad... What else is there, what works well, what should I avoid?
Thanks!

[Jake_Dragon]

There are several different ways, fan controllers and temp switches.

I like the temp switch in the head that triggers a relay at the fan.
Not something you want to go cheap with.

Jegs.com has several

[project34]

I agree with Jake but I would also put an override toggle switch in.

[46fordman]

I agree 100% with project34 and have always hooked mine up this way with no problems

[35hotrod]

Centech FC-2P fan controller. Self contained with relay, uses temp guage, totally adjustable from inside the car. Integrates withA/C if needed. Been using them for years, they work like a champ.

[wave1957]

I love that Centech idea, thanks! I may have to go with this; I guess I was secretly hoping for something like that, that does not require fitting another sensor on the engine...
Any other ideas?...

[DENCOUCH]

I would consider using a timed-to-open sensor as well. I would have it wired in addition to your regular sensors, but with its own power and overcurrent protection.

It would come on or allow the fan to continue to cool after the motor was shut down and the coolant began to heat up from the residue heat of the motor.

Just an idea as long as you are fishing for ideas.

[freedom53]

got a source for the timed-to-open sensor and perhaps a simple schematic re connections?

[DENCOUCH]

Originally Posted by freedom53

got a source for the timed-to-open sensor and perhaps a simple schematic re connections?

You might find them a bit on the spendy side. I am sorry, but it is not a sensor that you would use forthis, but a NOTO relay (Normally Open, Timed to Open).

You would require on that would handle the amp draw of your fan, and would be wired in place of the fan control relay that you have in the circuit at the moment. The control voltage and the line voltage would both be 12 volts. The good ones have the timing range adjustable.

Google NOTO relays. Try Grainger.

Good luck.

[SSedan64]

Variable Speed Control Part# 31165-VSC
Attaches to or near the electric engine-cooling fan. Senses coolant temp. via the radiator core and sets fan speed from 60% to 100%, depending on built-in fan thermostat setting. Thermostat range: 155 - 220 degrees Fahrenheit. Allows greater control over engine temp: reduces charging spikes and current load on charging system. 45 amp max. load. Directs fan to run for 30 seconds after vehicle is turned off.

http://www.flex-a-lite.com/auto/html...cessories.html

http://www.flex-a-lite.com/auto/31165-99943.pdf

[kidashley25]

The fan remains running after the vehicle shuts off in order for the engine to cool down. Once the motor cools down sensors trigger the fan to shut it off.

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[cucumber1949]

I've used a fan switch from DeRale ( p/n 16749) about $40. Comes with a pipe thread probe to insert in the intake's water jacket. Unit can also come with a radiator probe instead (different p/n). Adjustable trigger temperature. Has a lead for turning on with the a/c clutch, and has a manual override switch lead. Uses a standard Bosch automotive relay package so the relay can be easily replaced on the road if it fails - never happened to me yet but I carry a few in the car anyway. I have mine set to turn on at just below 200 degrees F and it turns off about 180-185.

[Dirty Biker]

I know this one. A motor only produces alot of heat when it does alot of work right? So just turn the switch when warm. Mount ya a cool looking fan switch somewhere and if you ever sit in traffic you can turn the fan on, Maintain 160 degrees. Maybe. Works on mine great.

[joe_padavano]

I've never understood why one needs a hundred bucks worth of electronics to turn a fan on and off. The factories used a simple on/off thermal switch, cheap and reliable. Kemparts P/N RF54, used on mid 80s-early 90s Chevy full size pickups to control the optional electric fan. $25 from RockAuto: