Ok so you have verified that the fans work so you know the electrical path from battery to fans is fine. So it must be something to do with the signal path from the computer or from a sensor to the computer.

I would start by finding the water temp sensor. It is what is called a negative coefficient thermistor. Basically as the water temperature goes up the resistance across this sensor goes down. Without getting into all the electrical garbage describing what voltages you should see out of the sensor and when (it gets complicated) you should be able to use an Ohm-meter to measure the resistance across the temp sensor when the engine is cold and then warmed up. Just unplug it and while the engine is cold you should get a very high Ohm reading. Some cars have as high as 10000 ohms of resistance. But keep the meter on the sensor as the car warms up and that reading should go down by quite a lot. If the sensor is working properly, by the time the car is warm the resistance reading across that sensor should have gone down by quite a bit. I don't know what it would be on the Focus.

If you want to know more confusing things about this, here is a good article. Just scroll down to where they start talking about thermistors because that is where it applies to this.
http://www.asashop.org/autoinc/may98/techtotech.htm

 

Oh and I should mention that on the Zetec its not actually a coolant temp sensor. Its a cylinder head temperature sensor. It works the same way and for the same purpose but you won't have water flowing out of the hole if you remove it for whatever reason. And it should be located on the side of the cylinder head. I believe the transmission side.

 

ok thanks i'll check that out.. but what still puzles me is no mater what. the ac will not turn the fans on. and i herd that as soon as you turn the ac on, the fans should kick on full speed no mater what the engine temp is. and mine is not.

 

Posted via FF MobileSilly question, try the new solenoid in the other slot? Could 2 have been bad?..... (didn`t notice a tested post...)

 

It very well should and its very likely the temp sensor is fine. Just covering all the bases first. It could be the cooling and AC fan problems are two different problems entirely. If the AC system is damage in some way the fans will never get the ok to turn on. But I doubt it cause it sounds like the AC works or worked before all this.

 

well i never realy used the ac cause it just blew heat.. but when i replaced my radiator and shroud, i took the ac thingy off too so i have no more freon in it... whould that cause a different cencore in the ac to not send the signal?

 

102C is 215.6F

The thermostat in your car is probably 92C or 197.6F

My fans don't come on until 107C or 224.6F which I'm assuming is the low speed fans. I've never seen anything in FORD's literature where the TEMPERATURE is stated when the fans come on at LOW SPEED and HIGH SPEED.

It's been awhile but..... if you pull the electrical connector off the fan assembly RESISTOR the fans appear to go into HIGH SPEED mode (might be a fail safe mode). I read somewhere when someone else did this they thought the fans went into the LOW SPEED mode after a few seconds, then after a few seconds more they went into the HIGH SPEED mode. Replace the connector and they shut off.

 

^^No his problem is the fans don't come on at all.

BTW how are you measuring the coolant temp? The temp gauge in the stock cluster isn't very accurate.

 

with the digital temp guage in the car. you know when you hold your milage reset button in wile you start the car. then keep it held in until your milage thing says test then you let go and it says gauge, and the gauges sweep. them you can toggle through haveing a digital spedomiter, tack and thermomiter. thats what ive been going by

 

^^ Sure - but we were attempting to see if he just wasn't reaching the temperature set point for the fans by fast idling the engine.

I would think that at 3000rpm you would only see a temperature rise if the fans weren't working. He saw a decrease - with no airflow? Hence my question about the fans - still not much of a drop in temp.

Something doesn't sound right.

 

mine is doing this exact same thing.. fans only come on after the car is to hott to cool down. do not turn on when i turn on the ac either but do work if i jump straight to the battery.

 

i just replaced my resistor and plug for the resistor and mine is doing the same thing, fans don't come on until the needle moves between normal temp(needle strait up) and and hot, and it doesn't cool it down fast enough, i have to open my hood and shut the car off, i was just checking my fan relays and found that my FAN 2(R10 in fuse box) is kinda melted on one corner

is this some thing i should worry about?????

 

Posted via FF MobileWell.... If it got hot enough to melt the case..... it probably isn`t passing much current anymore......