Low speed fan not working

Rjovi · Aug 23, 2011

Found a few threads on this, but none of them listed the fix. Low speed will not turn on, high speed works when I turn on my AC. If I unplug the sensor on the manifold (like I read on here to do) it will cycle through the low speed so I know the fan works. Also there is never power to the 10 amp fuse in the fuse box that controls it. Thanks in advance, I'm sure this has to be something simple...right?...I hope

Dino Dino Bambino · Aug 23, 2011

Sounds like the low speed fan relay inside the CCRM has blown. Try running a wire directly from the positive battery terminal (12v) to the wire going to pin 14 of the CCRM and see if that triggers the fan.

Rjovi · Aug 23, 2011

Thanks I will ASAP, can you give me a hint on which on is #14 please?

edit: nevermind, I see they are numbered

Rjovi · Aug 23, 2011

The fan will turn on if I jump pin #14. You didn't mention if the key had to be on or off, it won't do it with the key off (if this matters). So what does this mean?

HISSIN50 · Aug 23, 2011

Low speed should not run with the key off (with or without power on Pin 14).

Is the ECT calibrated?

Dino Dino Bambino · Aug 23, 2011

Rjovi said:
The fan will turn on if I jump pin #14.
So what does this mean?

It means that the low speed fan relay is good and the problem's elsewhere. The ECT sensor looks to be the most likely culprit.

Rjovi · Aug 23, 2011

Bullitt95 said:
It means that the low speed fan relay is good and the problem's elsewhere. The ECT sensor looks to be the most likely culprit.

Replaced that twice, the one on the manifold. I replaced it a few years ago thinking it was responsible for a different problem but it was my distributer pickup. So I had the one that was still good so I put it in, when it didn't fix it I figured maybe it was bad so I bought another, nope still no dice.

HISSIN50 · Aug 23, 2011

Swapping parts and checking the actual reading with a DMM are not the same.

Besides that, I think you're thinking of the gauge sender, not the ECT.

Rjovi · Aug 23, 2011

HISSIN50 said:
Swapping parts and checking the actual reading with a DMM are not the same.

Besides that, I think you're thinking of the gauge sender, not the ECT.

Definitely not talking about the temp gage, but I thought the ECT was the thing that threads into the manifold (horizontaly) and has a plug coming out the front. If you're facing the engine it is left side.

Chythar · Aug 23, 2011

There are two temp sensors on our cars: the ECT (which feeds the computer) and the CTS (which feeds the dash gauge). When facing the engine, the ECT is in the metal coolant pipe just tot he left of the distributor. The CTS is screwed into the lower intake to the right of the distributor. The ECT has two wires in its connector, while the CTS has only one. In my experience, a non-Motorcraft ECT or CTS has a higher rate of early failure or never working right in the first place.

Rjovi · Aug 23, 2011

HISSIN50 said:
Low speed should not run with the key off (with or without power on Pin 14).

Is the ECT calibrated?

I missed this, I didn't know they had to be calibrated. I have replaced it in the past without calibrating.

Rjovi · Aug 23, 2011

Chythar said:
There are two temp sensors on our cars: the ECT (which feeds the computer) and the CTS (which feeds the dash gauge). When facing the engine, the ECT is in the metal coolant pipe just tot he left of the distributor. The CTS is screwed into the lower intake to the right of the distributor. The ECT has two wires in its connector, while the CTS has only one. In my experience, a non-Motorcraft ECT or CTS has a higher rate of early failure or never working right in the first place.

Def the ECT then that I have replaced twice.

Rjovi · Aug 23, 2011

HISSIN50,
I found a thread where you were helping someone with the same symptoms and you told him to unplug his ECT to see if his fan turns on. He never responded after that so the next step was lost. Mine does turn on when I unplug my ECT. Is there a chance I have 2 bad ECT's?

Dino Dino Bambino · Aug 24, 2011

You'd be very unlucky to get two bad new ECTs but you can follow the testing procedure on this page to remove any doubt:

Ford Fuel Injection » Engine Coolant Temperature Sensor (ECT)

HISSIN50 · Aug 24, 2011

You don't need to calibrate the ECT but they can start to go south (i.e., fall out of calibration). In such a case, they report the wrong temp to the ECU but the temp they report is not necessarily out of reason (read absolute spec'), so the EEC does not spit a code. E.g., if your ECT was reading 180*F when the coolant is really at 210*, Pin 14 won't show 12V and the fan won't come on.

Disconnecting the ECT should make low speed come on. It's just a quick way of seeing if the EDF circuit is functioning.

If Pin 14 is not ever switching 12V (at 210*F or so. The ECT should read about 0.50V if you want to check it) but the ECT is calibrated, it gets more complicated to figure things out.

Rjovi · Aug 24, 2011

ok, let me get a more acurate temp gage to see where things are and I'll try both those things. Thanks

Rjovi · Aug 25, 2011

So what are the chances that I fixed a relay in the CCRM by jumping wire 14? When I tested the wire the first time, I swore it didn't turn on the fan but I thought maybe I wasn't on it good enough. Well it clicked then turned on.

So I bought another temp gage that I could watch to see how the ECT was acting and also checked the volts of the ECT. Everything was perfect, ECT started at 1.7 volts then dropped to .5ish then the fan turned on.

So I think I fixed the problem by jumping the wire ...probably only temporarely though

HISSIN50 · Aug 25, 2011

The issue is with the fan-switching on the control side (pin 14), not the relay itself (the relay doesn't need to be fixed).

What did you jump Pin 14 to? If jumping it to 12V, that's a common way to manually control the low speed.

Rjovi · Aug 25, 2011

The fan wouldn't turn on before at all, not at 210 degrees like it's supposed to. After I jumped #14 with 12 volts (Which made it turn on) it now works like it's supposed to. Now it turns on at 210 degrees , before it wouldn't, causing it to overheat, which is the reason for me digging into this.

All I'm saying is it is now working properly without me doing anything but testing stuff.

HISSIN50 · Aug 25, 2011

Since it's functioning intermittently, keep an eye on it.

Low speed fan not working

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