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Chrysler Repair/'97 caravan: cooling fans actuation problem

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Expert: - 8/15/2011


Question
I have a 97 dodge caravan 3.3l and the fans are not working. i have replaced the temp sensor behind the thermostat and the relay under the airbox the fans still will not turn on unless i unplug the temp sensor. any ideas or suggestions would be greatly appreciated.

Answer
Hi Bradley,
It would appear that the fan actuation circuits are working so you are left with the sensor circuit of the intereaction between the sensor and the coolant proper. Might there be an air bubble in the cooling system at the location of the sensor so that it is not able to sense the coolant's actual temperature? Are you certain that the coolant temperature is at the level that calls fpr the fans (204 F for low speed, 220 F for high speed, and do the fans come on when you ask for AC regardless of temp)? Have you measured across the terminals of the temp sensor when you believe that the temp has risen to the temp that would initiate the fans (it should be below 1,000 ohms). Those are the questions I would seek to answer.
Roland
PS Sorry for the delay but I just found your question in the 'pool' to which it had been referred by Kevin.

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Roland Finston

Expertise

I specialize in Chrysler/Dodge/Plymouth cars, minivans, and SUV's for the model years 1982-2008 based upon my 50-year DIY experience, factory shop manuals and wiring diagrams. I offer fast repair advice to help you minimize repair costs by helping you diagnose and do it yourself. Problems with electronically controlled engines and transmissions as well as body wiring problems are my specialty.

I take questions one at a time between 8am and 10pm CT and attempt to answer within 20 minutes. "Maxed Out" means I am answering another question of otherwise busy, so try again later.

There are answers on file to more than sixteen thousand Chrysler questions at your finger tips: put a few key words in the "find" box (above) or click on "view past answers" for a chronological list of my q and a's. Don't use "Add to this answer" if you still have a question...ask it. As to trucks and jeeps I only have manuals for the '04-'06 model years.

Experience

Five decades as a 'do-it-yourselfer' on domestic and imported cars

Organizations
Yahoo Autos Group called The Chrysler Lebaron Club (co-moderator)

Education/Credentials
Degrees in Physics/bruised knuckles.

Awards and Honors
"Top expert of 2010" and "2011" at Allexperts. Among top 50 experts for years 2006-2009 at Allexperts.

Quickest "average response time" at Allexperts (currently no. 1).

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