When does your radiator fan switch on?

[m3t4lm4n222]

I recently bought my 1993 Ford Festia L. It has 17K on a rebuilt engine, clutch, ect. In addition, the radiator, radiator hoses, thermostat, water pump where replaced 17K miles ago.

When I bought the car, I noticed the coolant temp gauge would show the coolant temp above mid point if I ever ran the car idling for more than 5-10 minutes. So I took it into my dads shop and replaced the coolant temp sensor and fan switch sensor. However, my temperature still rises. Here's a picture of the temperature after about 15 minutes of regular driving, then sitting at the bank to withdraw some money. As soon as I left and started driving, the temp returned to mid-point.


IMG_20140124_133549_467.jpg

I have also never noticed the fan switch on. So my question is..when does or is the fan supposed to switch on?

[skeeters_keeper]

If you unplug the fan sensor in the tstat housing with the car running (or just the key ON), does the fan run? It should. If it doesn't, try jumping 12v directly to the fan to see if the fan is at fault, or if there is a wiring issue.

[koRnhead]

Mine turns on when I turn it on, usually when the temp is around 205 on my gauge.

[m3t4lm4n222]

So is the fan supposed to be on at all times? I checked and when it gets to that temperature, it still doesnt turn on.

[m3t4lm4n222]

And do you happen to have a picture of the sensor plug. I see a sensor screwed into the thermostat housing.

[bravekozak]

Per the EVTM, the cooling fan temperature switch is normally closed and grounded. It opens above 97°C (207°F). The cooling fan relay is also normally closed. When you cold start your car, the relay opens and cuts power to the fan motor.
If the cooling fan relay solenoid fails, the fan stays on continuously.
If the cooling fan temperature switch fails open or loses ground the fan also stays on continuously.
If the cooling fan temperature switch doesn't open at temp, uh- oh, no fan.

[m3t4lm4n222]

I'm not exactly sure what all this means. I have replaced exhaust manifolds, alternators, radiators, ect but I know absolutely nothing about the electronics in a vehicle. What do you think the problem is specifically

[koRnhead]

Basically if you unplug the temp sensor, the fan should turn on, its a safety default thing. If you unplug the sensor and it doesn't turn on. The fan is most likely bad. Which is a great time to replace with something much better.

[skeeters_keeper]

Like I said, and others have repeated: the first step is to unplug the fan sensor in the thermostat housing. Turn they key on, unplug the sensor. If the fan comes on you have a bad sensor, if not its most likely the fan but could also be a broken wire in the fan/relay circuit.

is there an echo in here?... here... here...

[bravekozak]

Like Mr. keeper said. You have to work backwards. First check if your fan is good, then check if your switch is good, then check if your relay is good. Do you have a multimeter? Check for continuity in the fan motor. If O.K., then do what Mr. keeper said in post #2. See if you can get the fan moving.
We are all assuming that the FAN and METER fuses are good! Right? (better check the fuses first).
The fan will never ever turn if the FAN fuse is blown.

[m3t4lm4n222]

Yes, I understand this. However, as I have said, I see something screwed into the thermostat housing, but I am not seeing a plug. That is why I asked if anybody happens to have a picture of the plug that I should be removing.

I'm going to go check the fuse.

[m3t4lm4n222]

Meter and Cooling Fan fuses are A-okay.

[bravekozak]

It looks like this. That is the coolant temperature sensor. It provides a variable resistance signal for the temperature gauge.
The cooling fan temperature switch is the little one in the head, a couple of inches to the left of the thermostat. It has a push on bullet connector (green/yellow stripe wire). That is the one you need to unplug with the car in RUN to see if the fan comes on.

[m3t4lm4n222]

That looks to be the plug I have been seeing. So essentially I should be able to remove the wire running to it, turn my car on and the fan should come on?

[TorqueEffect]

It looks like this. That is the coolant temperature sensor. It provides a variable resistance signal for the temperature gauge.
The cooling fan temperature switch is the little one in the head, a couple of inches to the left of the thermostat. It has a push on bullet connector (green/yellow stripe wire). That is the one you need to unplug with the car in RUN to see if the fan comes on.

You got those backwards.

The fan switch is in the thermostat housing itself, the temp gauge sensor is the one to the left on the head. I know this for a fact.