Fan Not Working

MadeinUSA said:

I've got a 2000 V6 Mustang that was overheating. It's my daughter's. I noticed that the fan wasn't working when hot. Fuse under hood is good. It's a 2-wire fan,hot at fan shows 14 volts.

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Well..........Your problem maybe stranger than you realize.

Back ground. All of the V8 Mustangs have two speed fans. The two speed fans are three wire fans.

SOME model year V6's have SINGLE speed cooling fans (two wire fans). Where as other model years V6's use a two speed fan (three wire).

IF a single speed fan has been installed into an application requiring a two speed fan THEN one would expect to have the exact symptoms that you are experiencing. IE the fan would work on AC. However when the motor exceeded a certain temperature the PCM would call for high speed fan but because the wrong fan has been installed it can't. Over heat during stop and go traffic.

My Ford wiring diagrams indicate that a 2000 model year V6 Mustang uses a two speed (3 wire) cooling fan. I have to encourage you NOT to start "hacking" the car's wiring harness but instead use the correct part for the application.

OBTW in an application using a two speed fan, when the AC is on, the low speed cooling fan is forced on (yes that is correct. The low speed fan).

Soooooooooo. Is it possible that this is not a 2000 model year V6? For example a 2001 model year V6 uses a single speed fan.

Note, using a two speed fan in a single speed application would not have the symptom described.

If you want to answer the question about the temperature sensor an ODB2 scanner would make short work of your problem. Here's some information regarding an affordable Windows based unit.

ForScan ODB2 scanner w ELM327 USB
https://www.stangnet.com/mustang-forums/resources/forscan-odb2-scanner-w-elm327-usb.57/

And yes part of the CCRM is the fan controller. But think about it for a moment. If we assume that your car has a single speed fan AND the cooling fan runs when the AC is on, THEN the problem couldn't be in the CCRM.

Again having an ODB2 scanner that is capable of monitoring operational data would take a TON of guess work out of the trouble shooting.

I'm also assuming the fan connector itself is in good repair with no signs of over heating or dirty connections. Here's some information on how to confirm the voltage to/from the fan.

Howto perform charging system voltage drop test
https://www.stangnet.com/mustang-fo...perform-charging-system-voltage-drop-test.56/

Final note, IF you have confirmed voltage at the fan plug and the fan still isn't working look at the fan itself. Think for example worn bearings. Why is this important? Because in single speed applications the fan is protected by an automatic resetting circuit breaker (CB). This could explain how it's possible for the fan to appear to come and go.

Question: When does the motor over heat? During stop/go driving? Long expressway trips?

If the motor only overheats during stop/go driving and maintains correct temperature during expressway driving my educated guess is the cooling fan is drawing too much current and tripping out the circuit breaker. Why? Because the fan is not needed when the car's speed is above 45 MPH.

Yes there is a bench test the CCRM. The BEST way to test the CCRM is with a two way ODB2 scanner. Simply use the ODB2 scanner to "command" the fan on. Depending upon what happens when the ODB2 command is issued (OBTW the ODB2 scanner mentioned earlier in this thread WILL do this).

With ODB2 scanner it will to find out what the PCM "thinks" the ECT temperature is.

The other way to bench test is with a set of wiring diagrams and some test with leads and jumpers. A set of wiring diagrams is what is needed. If interested in getting a set for yourself I maybe able to help. PM if interested.

But..............................IF this is a 2000 model year AND the body harness fan harness truly only has two wires THEN someone has used the wrong body wiring harness. Further the symptoms you are experiencing should be EXPECTED.