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Compressor running when not turned on?

I have an '02 Taurus with 85k miles on her that I just bought. Today when I was checking something under the hood I noticed this metal line cold and dripping
with water...

Sorry the pic is so huge. I tried to reduce it. If you get over to the middle of the picture and go down you'll see a pipe with a white box around it.


I had the air on but turned to the position of arrows pointing out of the dash and floor vents only. The defrost or a/c function was not selected. It seems
to be doing it consistently. I haven't traced all the parts of this car's a/c system yet but I don't know of anything else under a hood that turns cold and
sweats. Why would my compressor be working when it's not selected? What tests should I run?
Last edited:


crank polisher
Very courteous of you to update. Thanks.

Never A/C'd on a Taurus myself, but on the trucks it's common that the compressor runs any time air to the defrost vents is selected, including mix. The A/C pulls moisture from the air, and keeps the windows clear. Possibly the same rationale on your car.

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Charter Member
By design, compressor engagement is possible in all positions other than vent, floor and off.

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