1989 Plymouth Horizon • 41,000 miles

Replaced water pump, thermostat, hoses, flushed system. Car always ran a little cool in summer but heat was hotter and thermostat said it was running warmer. Now in winter it is running just above "C" and very little heat. I blocked off 3/4 of radiator and still running very cold. I did notice the cooling fan started running when just one line above "C"then temp would drop and fan would shut off. Could it be Coolant Temp Sensor, Temperature Switch or Relay for Radiator fan motor. In what order would you replace or what else could it be? Thanks
January 5, 2012.

If the cooling fan is coming on that soon, that is the problem. My first guess would be the coolant sensor. Here is how it works. The coolant temp sends a signal to the comp, then the comp to the relay, then the relay to the fan.

Was the coolant temp sensor now the fan goes on when the car is a lot hotter. Still runs cool but that is just the way it was made. Thanks

Jan 15, 2012.
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Jan 18, 2012.