Electric fan users......sensor or switch?

I like the idea of a switch but hate the thought of forgetting to turn it on and don't like of sensors not being accurate or just not working...What are you guys using?

 

Use a sensor to trip a light so you remember to hit the switch......

Or just use a switch and LOOK at your gauges, that's what they're there for....

 

I use a fan bolted to a pulley run by the engine but I'm silly that way.

 

Maybe an air-cooled mill is the way to go..

 

On my roadster, I had a sensor that worked really well for a while, then not so much.....

Replaced the sensor, and tried to get it to work right. Not so much.

Settled on turning the fan on when the 12V buss is activated. Not very sophisticated, runs the fan if you are listening to the radio while parked (i.e., Speedweeks...), but no problem forgetting to turn the damn thing on.

By the way, my coupe has a older-style thermal switch that isn't much to look at, but has performed flawlessly for quite some time. I think some of the later model switches that screw into the intake manifold work well (usually activate a relay to power the fan).

 

i use both i have a sensor for the bigger of the two fans and have the smaller fan on a switch incase i ever need a little extra cooling

 

I used one from pepboys that works good. I learned if it has streetrod in the title it costs more.

 

A engine temp sensor that turns on a relay that turns on the fan.

Unless you are using a switch that is rated at 30 to 40 amps you will burn it up not using a relay.

 

I'm using a painless sensor that screws into an intake water passage with no problems.

 

I use a thermal switch that screws into the intake manifold/water jacket. It is a grounding switch, which means that it only passes electrical current when it reaches its preset gradient of 190 degrees. The electric fan is controlled by a heavy duty relay, and the relay is grounded thru the thermal switch. This is a pretty foolproof way to go. The engine heats up untill it reaches 190, the thermal switch then closes the circuit to ground the relay, and the relay closes to pass power to the fan. When the engine cools off to below 190, the thermal switch shuts off current flow and the relay opens stopping the fan. I use a Dodge minivan thermostatic fan switch, NAPA part #FS120, and they cost about $55.00

 

I have used both systems. I like the sensor and relay ,If you have a/c you can set it up for the fan to come on with the air.

 

I use a temperature sensor screwed into the intake manifold. This sensor activates a relay which starts and stops the fan. I also incorporated a manual override switch which will bypass the sensor in case of failure.

 

I use a switch with a relay. But I'm a serious gauge watcher when I drive, so I don't forget. Also my car runs pretty cool so I just switch it on if I'm in a stop and go situation.

 

sesnor with a relay , and a switch to do it manually too

 

I run a switch through a relay but the ign. switch kills it all because I've been known to forget to turn the fan off.

 

If I run electric fans I use a sensor with relay and an over-ride switch to bypass the sensor if needed. All is powered through the ignition switch. Always use 1st quality parts for this, including the fan. It's cheaper at this stage than after the engine goes through a meltdown.

 

Mine runs off a relay connected to ignition, runs all the time engine runs, never overheats never any problems.

 

I use both and both are run through a relay.

 

I haven't needed to install a fan, yet. Previous car had a 15 or 20 A switch and it got pretty warm. I gotta 35 A switch for when I get around to it.

Thanks,
Kurt

 

So if running a sensor it should be wired to the ign. switch, meaning that it would shut off when you turn off the key?....Shouldn't it be wired hot all the time so under a hot condition it'll continue to cool after the key is turned off? {which is when the coolant gets the hottest}

 

My view reguarding this is you would only be cooling the water in the radiatior once the engine stops, and the water pump is no longer circulating coolant through the engine.

So to be it seems like a waste of battery power at that point.

 

i have it on a switch right next to the fuel pump switch . and they are connected together the two toggle s that way you never forget. you have to turn fuel pump on to go simple keep it simple and it always works .

 

I got two small fans as opposed to one big one. One 11" spal fan cools my Small block just fine.

I have #1 hooked to a sensor from a Neon a 12 dollar part and fan#2 hooked to a switch. Both are run through relays.

The sensor is a 185 degree sensor, when my temp gauge says 185 the fan comes on. Never had a problem with it in about 2 years. But if it ever takes a dump I have the backup system.

In two years I have turned the second fan on once, it was over 100 degrees out ( I think the bank sign I was stuck by said 104) and I was there for about 15 minutes in traffic waiting to get through the light.

 

If you use a switch only through a relay , take it from experience, put a obnoxious little LED light on the dash so when the fan's on the light is on and vis versa. Even with a Thermo switch it is a good idea to also include a toggle in the system so you can give the fan motor a little longevity by switching it off going down the interstate, when it is not cooling then anyway.
the Dickster

 

i more-or-less agree with roadstar.

but, if the thermostat is still open (which it will be until the engine cools down some), water will continue to circulate due to (insert correct word here; convection, thermosiphon, etc.). that is; the hot engine water will rise and be replaced by cool water drawn in from the radiator through the lower hose.

when the thermostat closes, this will cease though.

not a very sophisticated answer, but you guys prolly understand what i'm saying better than i'm saying it.

however, will this justify the battery drain? who knows?

 

As others have mentioned I too run a sensor in the intake. However there is a sensor/control (?) on the market that you can set to allow the fan to run up to 5 minutes after you have shut the engine down. This is available from "Hotronics" I believe. Good luck ... and stay cool man!

 

The coolant in the cylinder head will heat up for a short time after the engine shuts off, but not the coolant in the radiator. Unless the engine's running, it's not producing heat so I see no need to run the fan if the engine isn't cranked.

 

i'm going with Dickster on this one. a couple month's ago i installed a swap meet find 15" diameter electric fan for my sbc. i put a 50A toggle switch and relay in the circuit as well. of course it was only a matter of a day or two before i got out of the car and walked away and the fan was running then there was the day i forgot to turn it on. so i tapped into the iginition switch and now i leave the toggle switch on all the time so the fan turn's on and off with the iginition switch. the bright light on the dash sounds like what i need. i will probably pick up a 150W bulb and mount it on top of the tach the good news is the fan appears to be doing the cooling duties just fine but i won't know for sure until spring and summer arrive and bring the warmer and hotter air temps. my initial driving tests in stop & go traffic, multiple traffic lights in a row and simply idling for 20 minutes while parked seemed to indicate success. mike

 

Use a fan switch from an early 90's camaro or firebird. It screws into the intake manifold and will provide a ground to a relay at about 190-195 degrees. You can run the other side of the relay coil to your ignition switch so it will never get left on. Plus this way it only runs when needed(temps above 190) which will make your fan motor live longer.

 

Continuing to run the fan after the engine is shut down only cools the radiator. Wont help cool the engine unless you have an electric water pump circulating the coolant too.