engine fan question

[deaf_rattle]

the sensor that determines when the radiator fan comes on, what conditions does it need to switch on and off?

Just wondering as im trying to work out what to do with some sensors and stuff and best place to put them etc.

cheers

[KE20]

it needs to be in the water,some have them in the head next to the thermosate and onthers have them in the bottom of the radiator. then there are 2 types of sensors, the ones that are one when cold and off when hot or the oppisite.

[deaf_rattle]

true
reason i ask, is because i thin kthe 20v has it on the cold side of the thermostat.
I put the ae92 temp sensor in there for the gauge and it did funny things. (would read cold and sometimes go up a little bit) but figured that was because the thermostat was opening and closing etc, and so now i have switched to using the 20v temp sensor for the gauge which is on the hot side of the thermostat.

so trying to work out if putting the ae92 fan control sensor on the cold side of the thermostat is the best thing to do.

fan is currently on all the time

cheers

[Levin]

The radiator fan in my old 20v levin used to just about NEVER come on. And would very rarely read the normal half way on the engine heat dial thingy. And it always sat on cold when I was on the open road in 5th gear. Nothing ever blew up, but it was just real weird.

[Rick]

The radiator fan in my old 20v levin used to just about NEVER come on. And would very rarely read the normal half way on the engine heat dial thingy. And it always sat on cold when I was on the open road in 5th gear. Nothing ever blew up, but it was just real weird.

I would say without a doubt that would have been caused by a faulty thermostat.

[Ae92typeX]

...

fan is currently on all the time

cheers

Have you still got aircon?, or if not have you bridged the sensor so the fan is not always on?
just another possibility

[matt dunn]

true
reason i ask, is because i thin kthe 20v has it on the cold side of the thermostat.
so trying to work out if putting the ae92 fan control sensor on the cold side of the thermostat is the best thing to do.

fan is currently on all the time

cheers

Have you still got aircon?, or if not have you bridged the sensor so the fan is not always on?

You need to earth the wire to make the fans stop,
and the circuit is from the relay, in and out of the a/c pressure sw, and then to the sw on the cold side of the thermostat.

the reason it is on the cold side.

You dont want the fan to come on when the engine is warm,
you want it come on when it is hot.

If the water on the cold side of the thermostat is cold, then to cool the engine down all that needs to happen is the thermostat to open.
no need for the fan to come on.

When the water on the cold side of thermostat is hot, the thermostat opens and the water flows through the engine and radiator, but as there is no cold water there the t/stat stay open and the water keeps heating up untill the sw turns on.

Thermostat's usually open at 82 to 85 degree's
and the fan sw operates at 95deg.
Remember that the system is under pressure so 100 deg is not boiling, it's higher.

[Rob]

If the sensors are not exactly the same they will give different readings

[matt dunn]

If the sensors are not exactly the same they will give different readings

A switch is a switch,
sensors have to be correct type's for the gauge but the switch's are all interchangable on toyota's.