Six-pack o' beer to the one who nails this one for me...

[JumpinJabroni]

Here's the deal - I'll buy someone up to $10 in beer for correctly diagnosing this one for me. It's a pain in the ass, and I'm tired of dealing with it.

1992 Ford Escot with 1.9L 4-cyl

Problem is radiator fan not running when the engine is on. Resulting consequence is that the car overheats in slow or stop and go traffic, but runs fine when at over 30 MPH (air pushing through radiator cools it sufficiently).

Here's what I know:

The fan itself does work fine - tested by directly connecting to battery. Connecting the negative and positive for either postive lead result in a spinning fan (fan has two speed operation, hence the two positieve leads). NOTE (important later on) - this testing process works even when the engine is on.

The fan relay located in the engine fuse box *appears* to work fine. I spent some time at AutoZone yesterday looking at it and the new one I tried works the same as the old one. *HINT* I can force the relay closed with my finger, and the fan will turn on as long as the engine is off. Once the engine is turned on, the fan stops spinning, even if the relay is closed.

The temperature sensor located near the cylinder head *appears* to work fine. Again, I replaced it at AutoZone, and the same problems occur. In addition, a test light placed at the location of the relay lights up when the engine gets hot. In addition, when the engine is hot, I can actually see that the relay is closed, but the fan will not spin.

There you go, boys n' girls.

Free Beer on the line!

Thanks in advance.
J

[mightymoose_22]

I could be wrong about this, but I will say this for now so you have something...

If you are looking at the fuse box in the engine compartment and looking at the fuse labeled "cooling fan" (if this is the one you say you are closing manually), you may want to divert your attention to the ignition relay. I believe power to the cooling fan first goes through the ignition relay, so that might explain why it is not working once the engine starts.
Hope that made some sense... I will get out a wiring diagram and see what I can find for you. Logic tells me it is something in that fuse box.

[mightymoose_22]

Well, after a little further investigation i can tell you this:
You should already know the fan motor and the temperature sensore are fine. It appears the cooling fan relay works fine.
The only other things that seem to come on to play are the Engine fuse and possibly the Meter fuse (both on the fuse panel under the dash), and The EEC (and I doubt that is the problem. Otherwise it is a faulty wire.
My best guess at the moment is for you to check the condition of those fuses under the dash.

[mightymoose_22]

Well... the more I have thought about it, the less what I said previously made any sense. There really is not that much in this circuit. A bad fuse would have other things inoperative. You say you know the realy is OK and the temp sensor is OK. If there was a problem in the wires I would htink youwouldn't be able to get the fan to run at all... the only thing that remains in the middle of all this is the EEC.
I am not certain how to go about troubleshooting the EEC.
I do have one question for you... when the engine is running, will the fan come on if the A/C is turned on?

[Brownsugar37]

Its funny that you are experiencing the same problems as I am. The funny part is, is that my car never over heats whatsoever. But why doesn't my fan come on. When I turn on the a/c it kicks right in.

Also, I am experiencing a jerking motion as I increase in speed which I am diagnosing as my oxygen sensor.

[mightymoose_22]

Well that about settles it for me... if, when the motor is running the fan does not come on, but the fan DOES kick on when the A/C is turned on, the problem is with the low speed relay, or its wiring. You have a high speed relay and a low speed relay. When the A/C is on the power is routed through the high speed relay, otherwise it defaults through the low speed.
Hopefully this will steer you the right way.
No, I am not having this problem... you must have read my other posts regarding cylinder ID circuit and timing.
Do you have a wiring diagram? If you still have trouble with this I could scan and email you a copy of the diagram.
Hmm... one more thought just struck me... maybe the car IS overheating and you just don't know it? You replaced the temp sensor, but what if its wire is bad?

[JumpinJabroni]

Originally Posted by mightymoose_22

I do have one question for you... when the engine is running, will the fan come on if the A/C is turned on?

I'm not sure, mightymoose_22, but I will try it hopefully tommorrow. I'll keep y'all posted.

[mightymoose_22]

Your little problem has caused me to start flipping through the ol' manual.... here is an interesting statement:
"The air conditioning and cooling fan controller module is operated by the computer, the coolant temperature switch and the BRAKE LIGHT SWITCH. The controller module provides an output signal which controls operation of the air conditioning compressor clutch and the engine cooling fan."

The brake light switch??? I can' thelp but think it is a misprint.. I didn't see it in the wiring diagram... BUT... do your brake lights work?

That doesn't make any sense to me, but I am sure the people that wrote the manual know more than me.

[Brownsugar37]

Originally Posted by mightymoose_22

Well that about settles it for me... if, when the motor is running the fan does not come on, but the fan DOES kick on when the A/C is turned on, the problem is with the low speed relay, or its wiring. You have a high speed relay and a low speed relay. When the A/C is on the power is routed through the high speed relay, otherwise it defaults through the low speed.
Hopefully this will steer you the right way.
No, I am not having this problem... you must have read my other posts regarding cylinder ID circuit and timing.
Do you have a wiring diagram? If you still have trouble with this I could scan and email you a copy of the diagram.
Hmm... one more thought just struck me... maybe the car IS overheating and you just don't know it? You replaced the temp sensor, but what if its wire is bad?

Yes I have replaced the temp sensor. I do not have the wiring diagram. Could you at your earliest convenience send me a copy, if its not too much trouble.
If the car was overheating, I would smell the coolant and the coolant would be bubbling over, correct?

[mightymoose_22]

If you know the sesnor itsself is new.... what about the condition of the wire that connects to it? What does your temp gauge read?
The coolant would not neccessarily bubbe over. When the engine is running, squeeze the upper radiator hose closed and feel for a surge of pressure when you release it to verify that coolant is cirulating. The temp sesnor sits up in the heater hose. If coolant is not circulating the sensor may not be reaching a temperature to turn the fan on (in other words, maybe the thermostat is stuck or there is some other blockage).
I am still curious to find out if the fan will run after the A/C is turned on.
I'll need an address to send the wiring diagram to. You can give it in a private message if you like.

[Team otr]

first of you should not be able to touch the relay at all it should be in a little contained case. second replace the relay with a 10 more amp draw trust me in the long run itll help you out cuz its a two speed draw so youll need those 10 extra amps cuz the fan peaks out at higher amps then most escort fans. third your having thermostat problems,so do yourself a favor and replace it ( 1.9 liters like 180 deggree thermostats) Ill take corona.

[pugmasterson]

Team otr
first of you should not be able to touch the relay at all it should be in a little contained case. second replace the relay with a 10 more amp draw trust me in the long run itll help you out cuz its a two speed draw so youll need those 10 extra amps cuz the fan peaks out at higher amps then most escort fans. third your having thermostat problems,so do yourself a favor and replace it ( 1.9 liters like 180 deggree thermostats) Ill take corona.


94 Ford Escort 1.9 Automatic

This post solved my issue, I pulled relay that is located in a little black fuse box in front of the battery and took a look at it sure enough it was blown. Replaced the relay for $14.99 tomorrow I will replace the thermostat.


Many thanks Team otr

[UnexplodedCow]

Check the fan temperature switch. I drive a 1st gen Escort, but it still needed one. It'll probably be right around, or on, the thermostat housing. If that switch is bad, or the plug going to it, there's your problem.
As for someone else mentioning about the A/C kicking on along with the fan, I've heard of that happening. It's a design in the computer, to keep the engine cool because the a/c is using more power, and the engine has to burn more gas.

[UnexplodedCow]

Also, if there's something up with your computer, the old escorts had the fan controller module near the blower motor inside the car. I'm not sure about a post 90 model, but I'd start looking there.