1998 Saturn SW2 Runing Hot

If ur a/c works turn it on and see if the radiator fan comes on and stays on with the a/c on if that's ok then I'll give u the next step.let me know.

Yes the fan comes on when the ac is on.

[img]https://www.2carpros.com/forum/automotive_pictures/416332_2001_coolant_temp_sensor_2.jpg[/img ok if ur cooling works with the a/c then I would say u have a bAd coolant temp sensor there under 15 make sure u get a brass tipped one the plastic tipped ones crack.also check ur coolant temp sensor connector if it's corroded or green then replace it as well.becareful make sure the engine is cold u will loose coolant when u change it.if ur old sensor has a plastic tip see if it's cracked.that sensor controls ur temp gauge and turns ur fan on to cool the engine off at 222-226 degrees when they go bad they don't read the correct temp.in ur case it sounds like it turns the fan on then changes to a cooler temp within a few seconds turning the fan off again.let me know what u find.

Thanks for the info, can you tell me were is the sensor located their is one on the manifold can you tell me if that is the one? if not were can I find it.

Thanks

Iam so sorry it took me so long to get back to u I never got a email telling me u replied.on my last post I posted a diagram showing where the sensor was.no it's not the one in ur intake.that's the inlet air temperture.the one u want is screwed into the head follow the upper radiator hose to the head the right bellow that screwed into the head is the sensor it has two wires going to it a yellow one and a black one.make sure u check the connector too if it's corroded the replace the connector too it usually tens green when they corrod.make sure u get a brass tipped sensor the plastic tipped ones crack.let me know what u find.and again sorry it took me so long to get back to u if I would have known u replied I would have gotten back to u alot sooner.

I replace the coolant sensor, but the fan still does not come on, but when the a/c is on the fan comes on what else can it be?

So u replaced the sensor that screws into the head with yellow wire and the black wire?was the plastic tipped cracked?how was the connecetor was it corroded?was that white plastic piece on the back of the cannector that says a and b that tells u which terminal is which?if ur fan comes on with ur a/c and not when it gets hot then the most common thing that I have seen is the coolant temp sensor and the connector going to it.the only other thing I can suggest is u find something wrong with the connector going to it.or u can get a temperture gun they have them at harbor frieght if u have one around with cupon for like 20-30.monitor the temperture at the inlet where ur top radiator hose goes on the head with the gun and see if the fan turns on between 222-226 degrees.let me ask u this how high does the temp get without the fan comming on?let me know.

The temp go up to almost the red line but as soon as I start moving it goes down.

Some of the temp gauges get old and read higher then they should I have seen some fans not come on till it gets to the tip of the red.that's why I suggested using a temperture gun to see how hot it's getting the fan may very well come on at 222-226 and the gauge just reads a little higher.so I would check that out and if the fan doesn't come on about within that range then we have to get a scan tool to hook up to ur obd2 connector that will read engine data and see if ur computer reads within 10 degrees of ur coolant temp which is spec.