Cooling Fan on All The Time?

[Rider90]

I just got back from Wisconsin, say 50 miles or so, and for the first half I had my A/C on until I noticed my cooling fan going. Its only a dry 90*F out so I turn it off, roll down the windows, and I'll take the heat. The whole way home the fan was still on, which was about 25 or so miles. Not stop and go traffic either, just Route 12 all the way back which was moving pretty swiftly today.

I pull in my driveway, still going, so I pop the hood and my coolant level is still at the "FULL COLD" mark. The car has never done anything like this before, in fact I often praise it's ability to keep me frozen when it's 100*F out in traffic.

Just a toasty engine or can something be wrong?

[SergntMac]

Hard to say, check it again after the sun goes down? The air around you may be 80 degrees, but the car, and engine bay may be quite a bit warmer.

My fan comes on full speed at 200 engine degrees, like clockwork. I never thought of it as anything more than just being accurate.

[Blackened300a]

Just a opinion here, thats sometimes the symptoms of a thermostat stuck open

[grampaws]

Faulty fan coolant temp sensor (common fault)

this is usually separate from the dash guage temp sensor...
but usually located at that thermostat housing or on the
front coolant passage of the manifold...Note when the AC is
on the fan will stay on all the time this is normal..as long as
the temp guage does not go up above normal range there should
not be any dire consequences..unplugging the correct sensor
should shut the fan of and change the sensor (under WAR if possible)..
Fan should be off when engine is cold and AC is off..switch should turn fan
on between 180 and 200F..

[BillyGman]

Faulty fan coolant temp sensor (common fault)

..That's^ the first thing that came to mind for me too. There's a wire going into it, and that wire leads to the fan motor if my memory serves me right.And I believe that it is a common failure since I've replaced them in one of my girlfriend's cars before. It almost looks like a sparkplug . Below I've included two sketches of it that's taken right from my 2003 Ford shop manual for the Marauder. If you look at the two sketches closely, you'll see that it's located on that black metal coolant pipe where it runs verticle right behind, and to the side of the alternator(you can see the fins of the alternator in the sketches). If you plan on replacing the part yourself, then these sketches should be of help to you. The part doesn't cost a lot. Thread sealant should be used on the threads since it screws into a pipe where coolant flows through.

[Rider90]

Thanks guys, thats reason number 2 to see the dealer...so uh, maybe on number 3 or 4 I'll go :rolleyes:

[MENINBLK]

... and for the first half I had my A/C on until I noticed my cooling fan going...

This is where you started...

The Fan comes on with the AC. This is NORMAL.
Once the compressor kicks in and the High Pressure closes the switch,
the cooling fan comes on to make sure there is airflow across your condensor.
This in turn, adds heat into your radiator.
So after turning off the AC, the condensor will need to cool down
before the pressure is equalized in the AC system,
and then the temperture of your coolant will need to return to normal
before the fan will lower to a lower speed or turn off.

In +94F ambient temperatures, this may take longer than usual.

Check your AF level when the engine is COLD, and remove the screw
in the upper coolant pipe to add sufficient coolant to replace any AIR trapped in the plumbing.
Leave the cap on the reservoir while you are doing this.
Try doing this over a few days until all the air is gone.
You may notice your fan coming on less and less once the air is gone.

If it persists, then go to your dealer and let them check out everything electrical.

[Rider90]

Thank you Pete, I'll give it a shot.