Coolant Fan Temperature Switch

[caprice]

I converted from using a mechanical fan to an electric fan. The wiring set up is a kind of "limp home" style. I have an adjustable fan control temperature sensor stuffed into the radiator and a fuel pump relay. My complaint is that the wiring is all hanging out and the relay and controller hanging on by a few zip ties. Looks like a real hack job! My other complaint is even though it is adjustable, the fan comes on way too cool. If I turn the adjustment the slightest bit, it turns the fan on way too late.

Most stock electric fans are turned on by the ECM. Mine wasn't designed for that. Some though use a dedicated temperature switch, that screws into the engine. I spent several hours researching for different OEM switches, and only came up with finding out that a Pontiac Fiero has one BUT it doesn't switch until 225-239 degrees! too hot for me! Also found out old VW Rabbits (METRIC threading is a disadvantage too.) have one at 190 degrees, that is cooler than the thermostat I have, and want to keep. (thermostat is 195) Ideally I want to keep the temperature of the water at 205 or so. I want it hot like that for fuel efficency, but much more is not good for engine longevity.

Anybody know of any temperature switches that are about 205 degrees? I prefer a OEM (doesn't make which make) part or replacement part, to use as a universal part for a "custom application". Reason being for cost and availability. Prefer 2 speed, because my fan is 2 speed. Thanks for any help!

[Mentalic]

Only thing that I have seen that allows you to set the temp where you want is a variable speed fan controller like this vendor offers below. The variable speed seems like a good idea since it only runs as fast as you need.

http://www.dccontrol.com/

Please post your before and after electric fan FE numbers if you can. Also what type of original fan did ya have, fan clutch, temp controlled fan clutch or direct drive?

My 4 Runner has a temp controlled fan clutch that I have been considering replacing with an electric. I often tow a boat so I'm not comfortable just yet with switching due to concerns that the electric may not cool sufficiently while towing.

[DracoFelis]

Anybody know of any temperature switches that are about 205 degrees? I prefer a OEM (doesn't make which make) part or replacement part, to use as a universal part for a "custom application". Reason being for cost and availability. Prefer 2 speed, because my fan is 2 speed. Thanks for any help!
You might want to look at what I ordered. While it's not yet installed (it's going on with my new radiator, likely this week), I picked up the following adjustable radiator fan controller:
http://www.napaonline.com/MasterPages/NOLMaster.aspx?PageId=470&LineCode=BK&PartNumber=7709553&Description=Radiator+Fan+Temperature+Sensor+Kit

Now my car already has control of the radiator fan. However, my feeling is that the fan has been coming on at a lower temp than it really needs to (and lower than is optimal for FE). And with the stock arrangement, I have no way to control it. However, if we modify things to have the fan controlled by this new (variable) thermostat, than it should be trivial (just adjust the temp control) to experiment with different coolant temps and their effect on the engine and FE. Hence my desire to bypass the stock fan control, and instead go with an adjustable thermostat...

[tjts1]

Those variable temp switches that a lot of vendors like to sell are nothing more than hot water heater thermostats for your house. Completely inappropriate for a car. The problem with sticking a probe between the fins of the radiator is as soon as the fan comes on, the air rushing past sensors will cool it far below the temp of the coolant inside the radiator. It will never give you an accurate temp reading no matter how you set it. The solution is to use a sensor which is in direct contact with the coolant.

This is my electric fan conversion for a volvo. I used a temp switch hose adaptor from a late 80s Saab 900. The hose adapter can be found on the top hose in a Saab with a 115c temp switch. I installed it in the lower hose with a 91c temp switch. New temp switches can be bought at NAPA in any number of temperature ranges. Mine switches on at 91c and off at 87c.
Good luck
http://farm2.static.flickr.com/1150/685229352_8cacb35978_o.jpg

[brucepick]

I also replaced the original clutch fan with an e-fan. I'm using a holder out of a Saab just like what tjts1 showed above, in the lower radiator hose. Fortunately they fit my car's rad hoses perfectly. You can get switches for those T-fittings in various settings at parts stores. Mine comes on at 83 or 85 deg. C and goes off 5 degrees cooler. That operates the fan at high speed.

However mostly my fan runs at low speed only, via a relay activated by the brake light circuit. A brilliant idea suggested from Mapleleafer of turbobricks.com, who's mom's car kept overheating at stops. Brilliant because it ensures there's always at least a slight breeze over the radiator - so the engine doesn't have to heat up past some trip point for the fan to come on. That way, it mimics the clutch fan more closely than temp sensors do.

At highway speeds you really don't need to worry about switching the fan. I doubt there are many (any?) fans that provide more air speed than highway road speed. Mine does come on if I charge up a hill at wide throttle - well, I used to do that! But the fan is not what cools things down in a climb, it's the downhill at low throttle that cools things off.

[tjts1]

The electric fan is extremely quiet. Chances are you can't hear it over the engine at idle.

[brucepick]

The electric fan is extremely quiet. Chances are you can't hear it over the engine at idle.

Quite true. When driving I don't even hear it when fan is on high speed. I'm pretty sure he did tell his mom what he did but that's another story on another board, two or three years ago.

For my system, I rigged a dash LED that shows when fan is on. It doesn't tell me which speed but I know if my foot is on the brake or not so that covers it for me.

[caprice]

The problem with sticking a probe between the fins of the radiator is as soon as the fan comes on, the air rushing past sensors will cool it far below the temp of the coolant inside the radiator. It will never give you an accurate temp reading no matter how you set it. The solution is to use a sensor which is in direct contact with the coolant.
[/IMG]

Exactly what I am thinking. I found this web site that gives the specifications of ALL switches! Freaking awesome. http://www.wellsmfgcorp.com/~wellsmfg/ds_fans.php?switch=sw&submit=Submit All I got to do is pick one, and go to Checker Autoparts.

I switched to a small electric fan out of a V6 Camero the same time that I did the motor swap. It's too small. Daytime temperature are over 110 degrees here in Phoenix. It runs constantly during the day, and intermittently at night. It probably is taking more power to run it than a mechanical driven fan. Power loss by converting the energy to electric, via the alternator, power loss by the electric fan motor. I scored a radiator fan out of a Lincon Mark VIII for only $20. According to a lot of forums on the internet, these move a lot of air, and has no problem cooling large engines. This thing is a monster, I think it is bigger than the original fan. It has 3 wires: ground, high speed, and low speed. I am thing of putting in two sensors, one at about 205 to engage the low speed and one at 220 for full speed.

Thank you for the responses. I just scanned over them, will read them better tomorrow when I have more time. :thumbup: :thumbup: :D :)

[caprice]

You want the radiator fan to come on 10 degrees after the regular thermostat, right? Or is it 5 degrees?

[Raccoonjoe]

I've been told that the fan you've got...that Lincoln Mark VIII?? Same as the 2 speed Taurus fans....One of the best E-fans you can get out of a junkyard. I'm going to put one in my Jeep.....figured I would wire the low-speed up to the ignition (always on), then wire the hi-speed to both the OE wiring for the aux fan, as well as a manual switch.

[Bill in Houston]

The problem with sticking a probe between the fins of the radiator is as soon as the fan comes on, the air rushing past sensors will cool it far below the temp of the coolant inside the radiator.If I were trying to make something like this work, I think I would put the probe somewhere that the fan doesn't suck air through (or where it sucks very little through) and put a small piece of coroplast on the front side of the radiator to block air from blowing over the probe.

[caprice]

Bringing this thread back to the top, for results and update. ;)

Remember, I have been running a weak v6 camero fan with a radiator probe switch for a few months, all wired up all hacked looking with zip ties.:eek: Now putting in a fan out of Lincoln Mark VIII, known for being a junkyard jewel, because for $20 or so you get a fan that out performs most aftermarket fans. (It takes a lot of amps to run it, so you need 10 gauge wire, a big relay, and diode.)

Bought a radiator cooling fan switch/thermostat at Napa "for a 87 Buick Grand National" I wired it up this morning, and finally put in the Mark VIII fan too. I researched online for how to wire it up for low speed, and apparently, I don't think it is a two speed fan! Unlike some of the Taurus fans! I took it for a test drive, and it works. It "deep cycles" it seems. It runs for 30-60 seconds or so. The radiator gets cold, and I think it just takes time for the cool water to flow through the whole engine, to the thermostat housing, where I have my temperature sensor. Then it finally shuts off. Its not a bad thing, it won't be cycling as often as my old setup. So I went back home and I have hot wires.:thumbdown: :( I originally thought I could get buy with thinner wires and smaller relay, but as I said earlier, it doesn't have a low speed. So now I am just going to do it right this time, and finalize the wiring for this baby, the right way. a 75 amp relay cost a whoppin' $65:eek: (I wasn't going to pay that!), so instead I went to the junk yard hoping to find a high capacity relay. Most relay's AMP ratings aren't marked. But I found a 70 AMP relay in Large Ford cars. Also found an AWESOME relay box! Look for late model Mercury Grand Marque's. Surprisingly, they don't seem to come in the Ford Crown Victoria's, though. It is located at the top of the passenger fender. It is very small for a relay box, It holds one high capacity 4 pin relay, and one regular 4 pin relay. I discovered that a Ford 2 pin diode fits perfectly into the regular relay slot! This relay box demensions are about 4" by 2" and 4" tall. It mounts very easily too!:cool: :cool: :cool: Pictures coming soon.

So to summerise, 80 Bucks gets you the whole fan system that looks stock. 25 for the fan, 35 for the thermostat switch, 10 for the relay mini-box w/ relay and diode, and about $10 in wiring supplies.

[Telco]

Couple of things, the DC Control unit is an excellent piece. I've used 2 of them so far, in 2 different vehicles. I've had no problems with the temp probe taking its reading from between the radiator fins as is as the DC Control probe is insulated. I do know the Flexalite controllers have had a problem with this. The fix is simple, you put a little silicon across the front of the fin hole that the probe fits into.

The real advantage to the DC Control unit is it allows a constant temperature to be put into the radiator, so the temperature doesn't spike as it does with the simple thermostatic switch. And, it brings power on slowly instead of instantly, which is much easier on the electrical system. Having a constant temperature means you can run the temperature at a hotter level than with a spike system, and a constant, steady temperature is better for power and economy.

On top of this, only one sensor is required, no need for a low speed and high speed sensor. The fans don't need this because the factory sent them out this way, the factory sent them out this way because thermoswitches are cheap when you buy them by the million. The factory has since moved to direct computer control for the fans, but still uses the 2 level fan control because the hardware and programming is cheaper that way.

On the fans themselves, they are simple electric motors. They don't require either full power or no power, so there should be no concerns about using a factory fan with an aftermarket controller. They will work just fine.