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Vincent, Ford Senior Master Technician
Category: Ford
Satisfied Customers: 1450
Experience:  28 years as Tech.
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I have a 2002 Ford Focus ZTS , the cooling fan does not ...

Customer Question

I have a 2002 Ford Focus ZTS , the cooling fan does not come on via the temperature sensor. Can you please advise me ?
Submitted: 8 years ago.
Category: Ford
Expert:  Vincent replied 8 years ago.

The cooling fan is controled by the engine computer, not the temp gauge.

Tell me what is the problem, is the vehicle over heating?

Customer: replied 8 years ago.
If you run the car with the car sitting the temperature continues to rise until the car will shut itself down. When driving if you're running the a/c the car does not heat up, the fans operate properly and it does not heat up but if you're not using a/c the temperature gauge keeps rising. If using the a/c the temp says within range.
Customer: replied 8 years ago.
The fans do not cut on anytime unles the a/c is running. Whether driving the car or sitting in place it will shut down if a/c is not on.
Expert:  Vincent replied 8 years ago.

Check to make sure that both cooling fans are working with the a/c. If they are both working, (and it sounds like they are) check the fuse at location f2 in the Battery junction box. (30 amp) If that fuse is okay then you will need to check the resistor between the fuse box and the fan. The resistor is located on the radiator.

If the fuse is blown, that normally means that the cooling fans are going bad. The a/c relay side is feed with a 50 amp fuse, and when the 30 amp fuse blows then the fans are drawing too much current. The 50 amp will blow soon and when that happens you will not have any cooling for the engine.

Vincent and other Ford Specialists are ready to help you
Customer: replied 8 years ago.
The fuses are good, the resistor is good, we had already checked that before I sent message, Had checked everything we could think of but still have problem. Any other suggestions.??Yes, both of the cooling fans are working with a/c...We're baffeled.
Expert:  Vincent replied 8 years ago.

Check to see if you are getting power to the fans when the engine is running hot. The circuit is pretty simple except that the computer turn on the fans. It is possible that the temp gauge is reading high, but the engine temp is not high enough for the computer to want to turn the fans on. The computer uses a different sensor then the gauge does. If the gauge is reading high, but the engine temp is not high then the computer will not turn the fans on.

Have you pulled the codes out of the computer?

If you have a test light, make sure that you are getting power to the cooling fan relay. Keep in mind there are two relays, one high speed one (the a/c) and the low speed one. The one that you are chasing is the low speed.

The power for that circuit runs from the battery, through a 50 amp fuse (F6), to and through engine cooling fan relay, through the 30 amp fuse (F2) through the resistor and to the fans.

If you jump the relay and the fan works, then I would be wondering if the computer is even turning on the fan.

Customer: replied 8 years ago.
Finally found the problem the wire to the relay had melted and sometimes it was making contact and sometimes it wasn't. It had been in to an authorized Ford dealership to have work done on it in the past and apparently they had done some not so kosher things that had caused problems now. I can't give you all the specifics because I'm the middle person they're working on the car at another location and I'm trying to relay all the information so since I'm not a technician I probably haven't explained thing as good as they could. Oh, by the way, there were no soft or hard codes from the computer.
Customer: replied 8 years ago.
correction should be to the resistor assembly near the radiator not the relay.
Expert:  Vincent replied 8 years ago.

You are right the connection should be to the resistor not the relay. I was being chased out of the shop and was typing a little faster then I should have been.

I am glad that you found it though. Good Job. I would check the current draw of the fan though, as excessive current can cause the contacts to expand and melt.

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