1999 Ford Escort ZX2 cooling fan circuit

first the 2.0 Zetec engine has 120,000 miles on it.
the cooling fan began staying on after the car was turned off, and engine was cooled down.

We would pull the 40 amp fuse to shut off the fan (did not have money to repair at the time). did this 4 times before fan began to work correctly.

Once the money was in the bank, I purchased and installed a new temp switch, temp sender (for gauge) and a thermostat.

I checked the fan, and it works fine from the battery.

Upon the engine being started, and warmed up, the fan never came on, not even when the engine reached 220 degrees.

I am ready to trace the wiring, but am not sure where to start.
it would be great if I could bypass the computer and run direct from the temp switch to the radiator, but that would affect the A/C.

Any ideas would be greatly appreciated.

this is a mazada262. temp sensor for gauge has nothing to do with fan circuit. the fan running with key off tells me fan relay is stuck. engine cooling temp sensor that controls computor logic is a seperate sensor. and it also can keep fan on to long and their other drivably problem when this sensor not working.

hobbist, I only changed the thermostat and temp gauge sensor because they were in the same area as the switch.
This vehicle does not have a relay (go figure), I spent a great amount of time to find this out, and could not figure why they would not have installed one.

When I went to the Ford Dealership, they looked it up and found that the fan was ran from the computer, and the temp switch was what told the computer when to turn the fan on/off, then another circuit would energize the fan when the A/C was turned on. Other than that, there is a special breaker/fuse (40amp) that controlls the voltage going to the fan.

So you can see where I am stumped... I don't want to replace the computer, so I am hoping someone has had this situation in the past and would know what to check next.

Thanks for your information, this is exactly what I thought before diving in.

I talk with my brother on phone he is an engineer with ford motor dear born. unhook battery disconnect and reconnect plugs on computor two or three times could be moisture crossion on pin can cause this if not then you will have to change computor.get one out of junk yard off a escort or mazada 262 same year model its cheaper.but unrealiable go or no go possible ????.but a new one puts realiable as long you ground your body be for removing computor from package and stay grounded through procedure their are real sentsive to static charge off of clotheing .this is best answer i could come up with.

Man, you are awsome, that sounds like a plan, and I will try it.

**What makes me feel, and look like an idiot, is this.. I never unhooked the battery, so I bet the computer never reset.
*now I will check the system after reseting the computer, then if that doesn't work, I will change the computer.
We have a new junk yard called pick a part that I like going to.

Again, thanks for your help.
And tell your bro thanks too.