Cooling fan problem
02-01-2013, 04:33 PM
#1
Newbie - Just Registered
Thread Starter
Join Date: Oct 2012
Posts: 14
Cooling fan problem
Hey guys, so I have a 99 SE auto with 162k and it runs and drives great. Today on the way home from work I noticed that my temp gauge started slightly rising maybe 1/8 of an inch above the standard when I am sitting at the light, then when I start driving it goes back to normal. I got home and kept the car running and noticed both fans are on, when I turn the heater off both fans stop, turn the heater back on and both fans are back on. I shut the car off and let it cool for 5-10min, cheked the coolant and it was fine, and lo leaks, and it has a 1month old thermostat. So after it cooled down a little I start the car again and the fans are on right away and same thing when I turn the heater off both fans shut off.
Has anyone had this problem? is it a fan switch? a bad thermostat or water pump? or???
Any help would be appreciated.
Has anyone had this problem? is it a fan switch? a bad thermostat or water pump? or???
Any help would be appreciated.
02-01-2013, 07:00 PM
#2
Member
Join Date: Nov 2006
Posts: 164
You checked the coolant after letting it cool down for only 5-10 minutes?
Check coolant with the engine cold. The radiator should be full the the brim (no air) and the overflow tank between min and max.
The symptom you describe of temperature rising while waiting at a traffic light, then falling when the car is moving suggests a problem with the fans, but if the temperature rises while the radiator fans are running chances are there is air in the cooling system.
I don't know how the heater would directly switch the radiator fans on and off, usually the AC does that. But if the radiator fans never run unless you turn on the AC then perhaps the ECTS (which is not the same sensor that feeds the dash temperature gauge) is not working. If the computer always thinks the engine is cold it won't run the cooling fans and it will run rich all the time, causing poor MPG.
Check coolant with the engine cold. The radiator should be full the the brim (no air) and the overflow tank between min and max.
The symptom you describe of temperature rising while waiting at a traffic light, then falling when the car is moving suggests a problem with the fans, but if the temperature rises while the radiator fans are running chances are there is air in the cooling system.
I don't know how the heater would directly switch the radiator fans on and off, usually the AC does that. But if the radiator fans never run unless you turn on the AC then perhaps the ECTS (which is not the same sensor that feeds the dash temperature gauge) is not working. If the computer always thinks the engine is cold it won't run the cooling fans and it will run rich all the time, causing poor MPG.
02-02-2013, 02:22 PM
#4
Member who somehow became The President of The SE-L Club
iTrader: (19)
Join Date: Jun 2001
Posts: 16,033
Automatic Climate Control?
Yes - A/C compressor and fans run when outside temp is above freezing.
Turn the climate control off. Let the car idle, watch the temp gauge and fans. Make sure they cycle when/if the temp starts to rise. There are two sensors in the cooling system. One controls the temp gauge, the other sends the signal to the ECU which controls fuel trims and the cooling fans.
If the engine isn't overheating, fans are cycling normally, then one sensor might be slightly off. You can check them with an ohm meter. A resistance verses temp table is in the FSM.
Yes - A/C compressor and fans run when outside temp is above freezing.
Turn the climate control off. Let the car idle, watch the temp gauge and fans. Make sure they cycle when/if the temp starts to rise. There are two sensors in the cooling system. One controls the temp gauge, the other sends the signal to the ECU which controls fuel trims and the cooling fans.
If the engine isn't overheating, fans are cycling normally, then one sensor might be slightly off. You can check them with an ohm meter. A resistance verses temp table is in the FSM.
02-02-2013, 03:21 PM
#5
Automatic Climate Control?
Yes - A/C compressor and fans run when outside temp is above freezing.
Turn the climate control off. Let the car idle, watch the temp gauge and fans. Make sure they cycle when/if the temp starts to rise. There are two sensors in the cooling system. One controls the temp gauge, the other sends the signal to the ECU which controls fuel trims and the cooling fans.
If the engine isn't overheating, fans are cycling normally, then one sensor might be slightly off. You can check them with an ohm meter. A resistance verses temp table is in the FSM.
Yes - A/C compressor and fans run when outside temp is above freezing.
Turn the climate control off. Let the car idle, watch the temp gauge and fans. Make sure they cycle when/if the temp starts to rise. There are two sensors in the cooling system. One controls the temp gauge, the other sends the signal to the ECU which controls fuel trims and the cooling fans.
If the engine isn't overheating, fans are cycling normally, then one sensor might be slightly off. You can check them with an ohm meter. A resistance verses temp table is in the FSM.
If you have an automatic climate control, you must know the difference between AUTO and ECON. Auto cools the car using the A/C compressor in combination with outside air. ECON does not use the A/C compressor and just uses outside air. If you are in a cold region right now, you should be on ECON. Once you have this set, observe to see if your temp gauge still goes up and if so, check to see if the fans are running.
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