Efan switch location advice

[Devorak]

First I did a ton of searching and could not find answers to my questions. I have posted this in a different section but the most recent post is months old so i thought Id have better luck here where its more active, so here goes

my question, is this a good location for the thermal switch for my efan?

What does the sensor on the left control?

what does the sensor on the right control?

the left one is a one wire connection and the right is a 2 wire. Im assuming the left sensor is a switch to ground sensor that activates when it hits the proper temp. which is what my new sensor does. What does it activate? can I shove my sensor in there for the efan activation and splice that old wire to the switch?

Im thinking the 2 wire sensor goes to the dash temp gauge, and the one wire switch, when activated, tells the computer that its in normal operating range.

or im completely wrong and these two sensors do something else entirely and I need to find a better spot for my thermo switch.

SPECS:

94 4L ohv engine, manual trans, 4x4

any insight would be awesome thanks

Brian

 

[willindsay]

One wire sensor goes to your gauge in the cab. the 2 wire one goes to your computer.

Usually for a E-fan you to put the sensor near the flow of water for the radiator. Although I have heard of people putting it in the heater hose.

 

[Devorak]

Thanks for the info, it pointed me in the right direction I've since looked up how the 1 wire sensor works and I can not splice the wire in it seems. It is a thermosensor and will give a resistance reading based on temp and translates it to your dash Gauge. The one needing a home is a thermoswitch and give an all or nothing signal based on temp.

If they are wired together the dash would get no signal until the switch activated to turn the fans on, then it just sit there at one spot regardless of what the temperature might be doing in the engine.

Questions answered

 

[RonD]

Don't mess with the two wire sensor, that is the "choke" for your engine, it is called an ECT(engine coolant temp) sensor.
The ECT tells the PCM(computer) to run injectors rich and to advance the timing until engine warms up, so like the choke plate on a carb.


The best place for the fan switch is in the rad, often the sensor will screw into the drain plug hole in lower rad.

Also if you have A/C it is a good idea to install a relay that actives the fan when ever A/C is on.

The fan clutch setup uses rad heat to activate, just FYI.

 

[Devorak]

i tried unscrewing the rad drain plug, but it just kept spinning and I didnt want to rip it out of there in case I eff'd the rad. Ill be a little more forcefull and see where that gets me, thanks for the info.

 

[RonD]

Rad drain "bolt" comes out, once it feels like it is unscrewed just pull on it, it has two plastic progs that keep it from falling out when unscrewed and draining.
My '94 rad was completely clogged at the drain plug so had to pull the rad to flush it out.
Rad comes out pretty easy, but I don't have an automatic so no trans cooler.


I think there are some external fan switches as well, they are "wired" on thru the rad cooling fins, so when rad gets hot fan comes on.

 

[Devorak]

update:

heres how I solved the problem. Two 1 1/4" stainless hose barbs welded together, drilled a hole and welded a stainless 3/8" npt adapter. cut the upper rad hose and clamped in place