Midwst Posted August 1, 2005 Share Posted August 1, 2005 If the coolant fan kicks in at too high a temp...would changing the thermostat ever make a difference? I think the coolant temp sensor controls fan turn on/off. Link to comment Share on other sites More sharing options...
mwatt Posted August 1, 2005 Share Posted August 1, 2005 If the coolant fan kicks in at too high a temp...would changing the thermostat ever make a difference? I think the coolant temp sensor controls fan turn on/off. What kind of car do you have and how are you judging "too high a temp" ? By the reading on the temperature guage? If your car is OBDII, someone should plug a scanner into the under-dash OBD test port to determine the exact temp of the engine. Link to comment Share on other sites More sharing options...
Cougar Posted August 1, 2005 Share Posted August 1, 2005 The thermo switch for the cooling fan is seperate from the temperature gauge sensor for the gauge, if that is what you are asking. The sensor for the gauge is a thermistor type sensor, which changes resistance as temperature changes. The thermo switch is just a on-off type switch that closes when the temperature reaches a certain point and turns the fan on. The thermo switch is usually mounted in the radiator and the gauge sensor is mounted on the engine. If the thermostat is not opening far enough then the coolant will not be able to move through the radiator like it should and the cooling fan may turn on more than it should normally. The temperatures settings used for the thermo switch to turn on are usually between 212-220 degrees F I think. Link to comment Share on other sites More sharing options...
frag Posted August 1, 2005 Share Posted August 1, 2005 The thermo switch for the cooling fan is seperate from the temperature gauge sensor for the gauge, if that is what you are asking. The sensor for the gauge is a thermistor type sensor, which changes resistance as temperature changes. The thermo switch is just a on-off type switch that closes when the temperature reaches a certain point and turns the fan on. The thermo switch is usually mounted in the radiator and the gauge sensor is mounted on the engine. It all depends Cougar. On a 96 2.2L there is only one coolant temp sensor under the right side rear intake runner, under the IAC valve. There is no other sensor or thermo switch. This sensor sends its info to the ECU wich in turn uses it to trim fuel, activate the temp gauge, start the radiator fans, and maybe other things. I dunno when this new configuration began but I suspect it was already there in the 95 2.2 L. Not sure about that though. Link to comment Share on other sites More sharing options...
Cougar Posted August 1, 2005 Share Posted August 1, 2005 Thanks for the heads up Frag. I was unaware of that. Link to comment Share on other sites More sharing options...
frag Posted August 1, 2005 Share Posted August 1, 2005 My remarks, though exact for the 96, do not apply to mdwst car which is a 91 I think. Link to comment Share on other sites More sharing options...
Gnuman Posted August 1, 2005 Share Posted August 1, 2005 My remarks, though exact for the 96, do not apply to mdwst car which is a 91 I think. Actually, they do. On a MY91, there are two sensors, one for the guage, and one for the ECU, which does all the things you described above (except activating the temp guage). Link to comment Share on other sites More sharing options...
Midwst Posted August 1, 2005 Author Share Posted August 1, 2005 This is for a 95 Legacy, 2.2L. I have a friend who has had this problem on several american cars. He always replaces the thermostat. I found that strange since the CTS and computer turn on the fan...but it seemed to work for him. Link to comment Share on other sites More sharing options...
frag Posted August 1, 2005 Share Posted August 1, 2005 This is for a 95 Legacy, 2.2L. I have a friend who has had this problem on several american cars. He always replaces the thermostat. I found that strange since the CTS and computer turn on the fan...but it seemed to work for him. Maybe what he calls a "thermostat" is in fact a temperature sensor. Replacing the thermostat would only, by decresing the average coolant temp, decrease the number of times the fans would come on if the previous thermostat was "lazy", but it would not change the temperature at which the fan or fans would come on. Link to comment Share on other sites More sharing options...
Legacy777 Posted August 2, 2005 Share Posted August 2, 2005 Yeah, changing the thermostat won't affect when the fans kick on. They kick on when the ECU sees 200 deg F coolant. Link to comment Share on other sites More sharing options...
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