Radiator fans are not working

Tiny
ALLEN WOOD
  • MEMBER
  • 2005 CHRYSLER TOWN AND COUNTRY
  • 3.8L
  • V6
  • FWD
  • AUTOMATIC
  • 190,000 MILES
My van fans wont run unless you unplug the coolant temperature sensor. Here is what I have done so far:

Replaced relay behind bumper.
Checked all other fuses and relays.
Replaced coolant temperature sensor twice.
Replaced pressure transducer.
I have checked all wires at relay. I have power, ground and signal.

The fans will run when I jump the relay harness.

The fans will run when you unplug the coolant temperature sensor.

The fans will not run when AC is on.

The fans will not run when the engine reaches the temperature in which the fans should turn on.

Help!
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Monday, October 3rd, 2016 AT 3:56 PM

12 Replies

Tiny
ALLEN WOOD
  • MEMBER
I also removed G102 ground connection and cleaned with wire brush and reinstalled.
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Monday, October 3rd, 2016 AT 4:39 PM
Tiny
CARADIODOC
  • EXPERT
The fan runs when you unplug the coolant temperature sensor. The system is working. The fan ran, so there is no point in testing the fan motor, the relay, the wiring, etc. They all have to be working for the engine computer to turn on the fan relay when you unplug the sensor.

Radiators today are very efficient, and it is not uncommon for them to keep an engine sufficiently cool without the fan, even when standing still and idling for a while. If you think there is an overheating problem, use a scanner to view live data and see the exact temperature the engine computer is seeing. You can also view the "Inputs and Outputs" to see if the computer is commanding the fan on. If it is, but the fan is not running, that is the time to do testing related to that circuit.

For a long time, Chrysler turned their fans on at 210 degrees, and off at 198 degrees. That may have changed in recent years. GM typically does not turn their fans on until well over 220 degrees.
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Monday, October 3rd, 2016 AT 4:55 PM
Tiny
ALLEN WOOD
  • MEMBER
Thank you. I believe it is time to check the circuit. The fans not turning on causes the compressor to struggle. The vehicle has gotten boiling hot without the fans turning on. Time to take it somewhere with some technology I do not possess.
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Monday, October 3rd, 2016 AT 5:07 PM
Tiny
CARADIODOC
  • EXPERT
Unplugging the coolant temperature sensor, like you did, is the way we test the circuitry. Turning the radiator fan on is the default for safety. With a break in the circuit, there is no way for the engine computer to know coolant temperature, so the fan is turned on in case the engine is overheating.

What I am questioning is why the fan does not run when the AC compressor cycles on. I would be looking at whether there are two fans or just one. There will be two when the AC condenser is beside the radiator, and not in front of it. In that case there will be two relay circuits to look at.
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Monday, October 3rd, 2016 AT 5:48 PM
Tiny
JOSE RIVERA ACEVEDO
  • MEMBER
I have the same problem unplug the temperature sensor both fan turn on and I do not what to do now.
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Friday, May 25th, 2018 AT 6:35 PM
Tiny
CARADIODOC
  • EXPERT
Nothing. The circuit is working if the fan turns on when you unplug the coolant temperature sensor. The previous person never replied back to say if they had two cooling fans or one. Reread the entire conversation to get some ideas of what to look for. Specifically, the fan that cools the AC condenser should run when "AC" or "defrost" is selected.
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Friday, May 25th, 2018 AT 7:04 PM
Tiny
ALLEN WOOD
  • MEMBER
I have two fans. I had to replace the fan on the passenger side. For some reason it was not kicking on when it was supposed to.
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Friday, May 25th, 2018 AT 7:18 PM
Tiny
JOSE RIVERA ACEVEDO
  • MEMBER
That help with your problem?
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Friday, May 25th, 2018 AT 7:42 PM
Tiny
ALLEN WOOD
  • MEMBER
Yes it did. It has been running ever since.
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Friday, May 25th, 2018 AT 7:44 PM
Tiny
CARADIODOC
  • EXPERT
Do you mean working as it is supposed to, or it runs any time the ignition switch is on? If it runs all the time, there is likely an electronic relay that is shorted. I would have to do some quick research on that.
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Friday, May 25th, 2018 AT 8:15 PM
Tiny
ALLEN WOOD
  • MEMBER
My apologies. It has been in normal running order since the fan replacement.
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Saturday, May 26th, 2018 AT 1:24 AM
Tiny
CARADIODOC
  • EXPERT
Dandy. Carry on.
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Saturday, May 26th, 2018 AT 8:36 PM

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