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Dual temp coolant sensor/switch?

Ben824

NAXJA Forum User
Location
Woodstock, GA
I am looking to find a dual temperature OEM coolant sensor/switch from any make or model I can use for my electric cooling fan conversion I am planning. I heard a VW might fit the bill but haven't been able to find any specs on the switch or what year and model to look for. I don't want to fool with a $100 adjustable setup and I don't like the probe sensors that can fail which would happen to me on a road trip in the middle of nowhere leaving me stranded and screwed.

Anyone know of a sensor/switch I can use for this so it will kick on at two different temps for the two different speeds?
 
That dirtbound switch doesn't seem like a great option unless you want your fans running all the time..... first temp comes on at 185? that means the fans will be running constantly because it has a 195 thermostat
 
That dirtbound switch doesn't seem like a great option unless you want your fans running all the time..... first temp comes on at 185? that means the fans will be running constantly because it has a 195 thermostat


Switch temps used - depend on which end of the radiator will be used to locate the switch.

If say .... a 195* t'stat is being used and the desired running temp is about 200* ... then ...

Hot side of the rad ... The running temp can be constantly chased and hoped to be held in check - by a 195* temp fan switch with a 210*/220* overheating switch for a secondary fan ...

or ...

Cold side of the rad ... Primary fan is activated at about 175* and the 195* t'stat does its job - regulating coolant flow/quantity to maintain a desired 200* approx, running temp - with a higher temp , secondary switch activation for overheating scenarios.



The factory fitted fanclutch ignores 195* and 210* coolant temps ...

Its specced to engage at air temps behind the rad ... of between 165*-180* and disengage at between 135*-170*.

Those air temps are probably about 15* less than the coolant temp in the rad.

195*, 200*, 210* are t'stat housing, coolant temps ...

... to be achieved ... by the engine heating cooled coolant, flowing from the radiator ... and are not nescessarily - the ideal, fan activation temps to use.
 
That dirtbound switch doesn't seem like a great option unless you want your fans running all the time..... first temp comes on at 185? that means the fans will be running constantly because it has a 195 thermostat

Switch temps used - depend on which end of the radiator will be used to locate the switch.

If say .... a 195* t'stat is being used and the desired running temp is about 200* ... then ...

Hot side of the rad ... The running temp can be constantly chased and hoped to be held in check - by a 195* temp fan switch with a 210*/220* overheating switch for a secondary fan ...

or ...

Cold side of the rad ... Primary fan is activated at about 175* and the 195* t'stat does its job - regulating coolant flow/quantity to maintain a desired 200* approx, running temp - with a higher temp , secondary switch activation for overheating scenarios.



The factory fitted fanclutch ignores 195* and 210* coolant temps ...

Its specced to engage at air temps behind the rad ... of between 165*-180* and disengage at between 135*-170*.

Those air temps are probably about 15* less than the coolant temp in the rad.

195*, 200*, 210* are t'stat housing, coolant temps ...

... to be achieved ... by the engine heating cooled coolant, flowing from the radiator ... and are not nescessarily - the ideal, fan activation temps to use.

To add to what Carves said,...think Renix. They have a 185* temperature switch, 185* on and 170* off mounted in the radiator, the cool side of the radiator. Their electric fan do not run all the time. I am also using one to trigger the fans in my XJ. It runs almost straigh up 210* all day every day. The fans never run at highway speed and cycle on and off at idle or on slow city streets.

Carves did post a nice link to some very interesting switches. I will be saving the link for future use.
 
Ok so the lower temp switches are better to run than the higher temp switches? And which side of the radiator is the "cool" side? I have a good idea but would just like to have someone verify it for me.
 
Which side of the radiator is the "cool" side? I have a good idea but would just like to have someone verify it for me.

The hot engine coolant passes from the passenger side tank top thru the radiator core tubes to the drivers side tank bottom....; so the driverside tank is the cool side.
 
The hot engine coolant passes from the passenger side tank top thru the radiator core tubes to the drivers side tank bottom....; so the driverside tank is the cool side.

Ok so if use the lower degree temp switch would I put it in the cool side? Every write-up I have seen where guys use and switch instead of a probe, they put the switch in the upper radiator hose or the t-stat housing for obvious reasons as it it much easier to add this here rather than down on the lower radiator hose.

Where does dirtbound require their switch to be installed?
 
Try one of these dual temp switches P/N echfs151 from NAPA. You will need a tapped fitting you can get from a mid 80's Volvo (but wrong hose size) or from a place like summit and tap your own (20mm tap will be the expen$ive part).
 
Try one of these dual temp switches P/N echfs151 from NAPA. You will need a tapped fitting you can get from a mid 80's Volvo (but wrong hose size) or from a place like summit and tap your own (20mm tap will be the expen$ive part).
 
Good call on the switch seems like it would be perfect. I plan on running that switch with a Volvo controller if I can find one in the junkyard and the switch in a Saab 900 switch inline hose switch housing also if I can find one in my local junkyard. Seems like this would be the most inexpensive route to wire up my Taurus fan. Thanks for all the help guys!
 
Saab switches/plumbing, Volvo relay block, Ford fan? With a late model, you can also stuff the temp switches into the heater core inlet hose, which gives you a few more options for mounting the temp switches. Whatever you do, don't buy the Hesco adapter. It may be especially useful on 97+ XJs, but they obviously didn't bother looking at one.
 
Saab switches/plumbing, Volvo relay block, Ford fan? With a late model, you can also stuff the temp switches into the heater core inlet hose, which gives you a few more options for mounting the temp switches. Whatever you do, don't buy the Hesco adapter. It may be especially useful on 97+ XJs, but they obviously didn't bother looking at one.

I wouldn't use the saab switch just the inline housing for the switch as it is already tapped for a M22 thread. I am going to use a Volvo thermo switch in the Saab housing, Volvo controller, and Taurus fan mounted in the factory mechanical fan shroud. I am using the smaller Taurus fan from the 3rd gen Taurus. The 3rd gen Taurus has a inline resistor to knock down the votage and slow the fan speed for low speed which I also grabbed. The smaller fan still has three terminals on the motor but only two wires on the pig tail so I am just going to add an extra wire and run the resistor in one lead and straight power in the other. I am hoping this will do the trick for me so fingers crossed!
 
I also am looking for a temp sensor that has the fan come on at 210* and off at 190* or close to that. The volvo one works? What year, model? If not, which work?

'97 Cherokee/4.0
Factory one
276511.jpg
 
I finally landed on a switch from a BMW. BMWs of certain years came with two identical switches that came in two different operating ranges. One switch had a kick on for low at 180* and 195* high. The second comes on at 195* low and 210* high. That may seem low but you really want to fan to attempt cooling before the the engine gets hot, not when it is too late. I have yet to finish the install but once I do and I can get some time seeing how it works out, I can report back. There are not a whole lot of dual temp switches out there and even less of any information on them. If you don't like those temp settings I do remember a couple of volvo switches that came in higher temp settings. I have the part numbers saved somewhere if you would liked me to find them.
 
How exactly does this work? It gets plumbed in and it automatically turns on the connected efan at a certain temp?

It plumbs in either the upper radiator hose of the upper heater hose. Those two hoses are the fluid exiting the engine and heading to the radiator or heater core. This is when the fluid is the hottest and represents the temperature of the engine. The switch has three terminals, one supply, two leads for two separate temperature ranges.
 
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