Overcooling

Tiny
CALEBJ77
  • MEMBER
  • 2004 CHRYSLER TOWN AND COUNTRY
  • 6 CYL
  • FWD
  • AUTOMATIC
  • 95,000 MILES
I have a 2004 Chrysler Town and Country that has over cooling issues. I have replaced the thermostat and the coolant temperature sensor. I have a actron scan tool with live data monitoring. According to the scan tool the engine temperature sensor is reporting 165 degrees and the cooling fans are on. The gauge on the dash is also showing low temperature. Why would the fans come on and stay on before the engine warms up. When the engine finally manages to get to operating temperature everything runs
normally. This engine has no EGR valve if that makes any difference.
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Tuesday, December 21st, 2010 AT 1:23 PM

3 Replies

Tiny
KHLOW2008
  • EXPERT
Here is a description of the cooling fan system.

OPERATION
Powertrain Control Module (PCM) regulates radiator cooling fans with Pulse Width Modulated (PWM) signals to solid state radiator fan relay. Radiator fan relay control circuit supplies 12-volt signal to PCM. PCM then pulses ground circuit to achieve fan activation. Radiator fan relay provides voltage to fan motors that is proportional to pulse width received from PCM. Duty cycle ranges from 30 percent for low speed fan operation and 100 percent for high speed fan operation. This type of fan control system provides infinitely variable fan speeds, allowing for improved fan noise, A/C performance, better engine cooling, and additional vehicle power.

Operation of radiator fan relay by PCM is based on inputs from engine coolant temperature sensor, A/C pressure transducer, ambient air temperature from body control module, vehicle speed, and transmission oil temperature. PCM uses these inputs to determine when fans should operate and at what speed.

There is a possibility of the PCM being the cause of the overcooling.
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Tuesday, December 21st, 2010 AT 1:41 PM
Tiny
CALEBJ77
  • MEMBER
Thanks for the prompt reply and detailed information of the circuit. I was afraid you would say it could be the PCM.
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Tuesday, December 21st, 2010 AT 2:01 PM
Tiny
KHLOW2008
  • EXPERT
Too bad that seems the most likely cause.
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Tuesday, December 21st, 2010 AT 2:50 PM

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