Overheated during inspection!

Eleanor's Girl · Mar 4, 2012

For the past few weeks, the stang has been overheating. Come to find out it was a stuck thermostat so I replaced it and it was fine for about 2 weeks until it overheated again b/c the fan wasn't coming on. I replaced the plug and wires with parts from Ford and it worked. Then I drove it from my house to the inspection shop (about 25 miles) and still no problems and fan was working great.
Well, as soon as the inspection guy slapped the new sticker on the windshield, smoke and radiator fluid was everywhere! Today I put more fluid and water in it and let it run, eventually turning the A/C on high to make sure the fan still kicks in. Here's what I found:

1. With the A/C on, the fan kicks in like supposed to.
2. Once the temp reaches the "R" in Normal, the fan turned off and never came back on, causing smoke to start coming from what appeared to be between the degas bottle and radiator, and a strong antifreeze odor.
3. There were absolutely no leaks from hoses, thermostat housing, water pump, etc.

I was ready to start suspecting the water pump but after today, I think I still have a fan problem. Anyone with ideas or suggestions? I've never replaced a fan so what do I need to do? Thanks!

wmburns · Mar 4, 2012

The high speed fan is NOT working. Just the low speed. The AC runs on the low speed fan.

Start by testing BOTH speeds of the fan motor.

Eleanor's Girl · Mar 4, 2012

wmburns said:
The high speed fan is NOT working. Just the low speed. The AC runs on the low speed fan.

Start by testing BOTH speeds of the fan motor.

Ok, so is the process in the Haynes manual the best way to test this? And once I test it and determine it is the high speed that isn't working, how do I fix that?

wmburns · Mar 4, 2012

That depends if fan itself is working or not.

Your post does not state the MY of your car. But, the two speed fan has three wires. The black wire is common ground. The other two wires are the low speed and high speed. Use a jumpper wire direct to a +12 volt source. The fan should run when connected to each wire (one at a time). There should be an OBVIOUS speed difference between the two speeds.

If the fan does not work directly from a power source, then the problem is in the fan itself. Otherwires more tests will be needed. Wiring diagrams would be a big help if it gets to this.

If interested in the full Ford service and wiring diagrams DVD for your model year, I may be able to help. PM if interested.

Eleanor's Girl · Mar 4, 2012

I don't have a voltmeter so my dad and I used his amp meter and got a reading from the high and low speed wires. They both read at .69-.70 amps so there is power going through them. Again, I let it run for a bit (without A/C) and once it got to the "R" in normal, I began seeing faint smoke from the radiator area along with a burnt antifreeze smell and the fan shut off. I'm tempted to just replace the fan altogether but would be upset if that doesn't resolve it. Is it possible that it's soley an electrical issue and not the fan? Or both? Or just the fan? I'm ready to throw in the towel and pay a pro.

wmburns · Mar 4, 2012

Just wonding what kind of AMP meter did you use? Is it possible it's an AC clamp on amp meter? An AC amp meter will not read DC amps.

Also, are you aware the an AMP reading of less than 1 amp to run the colling fan couldn't possibly be right? Should be at LEAST 5 amps and possibly quite a bit more. The circuit breaker is set for 30 amps.

It's very easy to split the connector to the fan. Use a scrap piece of wire (or a battery charger) to jump power to the fan.

Better yet, a budget voltage tester is less than $10 bucks. Much cheaper than buying autoparts that aren't needed. Besides, if the fan is good, the volt meter is going to be required for the tests that will follow.

Eleanor's Girl · Mar 4, 2012

The meter we used did not read direct current but I was not aware of it needing to be at least 5 amps. My dad has been in the works with electricity and transformers so he it all made sense to him. We did multiple readings--with A/C on & without A/C. I guess, I'll go buy a cheap voltmeter tomorrow and do this again. So what if I do this test tomorrow and everything checks out? Then what? Thanks again for your help

wmburns · Mar 4, 2012

FWIIW, the GT Mustang fan circuit is and either or. By that I mean it would not make sense for there to be current in the HS and LS wire at the same time. Power is applied to the LS side or the HS side. Never both at the same time.

Are you a naturally worried person? FWIIW, your question has already been answered. But if you must know, if the fan checks out, the next subsystem to test is the CCRM.

BTW, it would help if the model year of your car was given.

Overheated during inspection!

Eleanor's Girl

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Eleanor's Girl

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