1996 saturn sl2 fan coming on late an over heating

yes
try having the fault codes read to determine the fault area
indicates a problem ambient temp sensor, problem BARO sensor or faulty MAF/VAF sensor

I believe the Saturn has a cam timing sensor, not a crank sensor. It is located right below the head, accessable from underneath the car. It controls your injectors etc.

i had 4 saturns, and the A/C never worked on any of them and they did not overheat. there is a sensor screwed into the head just above the bell housing. this sensor puts voltage on a relay when the coolant hits a certain temp. that relay turns on the fan in front of the engine. when the A/C is on, it goes around that circuit and runs the fan constantly. so if your fan is not running period, except when the A/C is on I would suspect the sensor, the relay, or the control computer. the relay is in the fuse box behind the driver side head light. it is the same relay as the one for the A/C so you can just switch them to see if the fan relay is bad.

replace the thermostant again this time get a hotter temp thermostant and buy it from the dealer, the other thing is that these cars are known for the temp sensors being bad this would give you the false reading on the gauge but would not affect the heat, if its taaking a long time then i would replace the stant and this time or before replacing the stant i want you to flush out the heater core, remove the hoses from the heatercore and use a water hose to flush water through the heater core, a plugged core will not throw heat or will start to allow water to flow when it gets good and hot to flow through the retricted core due to rust and crud, try the flush first and then try a new temp sensor if the flush helps the heat, hope this is helpful good luck.

Go to SaturnFriendsForums.com it's a great site with a WEALTH of info on saturn specific problem solving.

In the mean time have auto zone or other parts place read the codes for the service light,

MOST problems are caused by a bad water temp sensor on the right side of the engine down low ( looking at it from the front of the car ) it's called the ECTS sensor, get a BRASS one from auto zone for $8.00 it will solve a lot of problems that there may not be a code for.

Check your oil while warm. If it looks like chocolate milk, you have coolant in your oil. If your vehicle is cold, undo the oil drain plug and see if you have coolant coming out of the oil pan. You can also rent a Block Tester at Autozone for $25.00 (you get the 25.00 back when you return it) and buy some block test fluid ($8.99). You get a lot of fluid and will be able to check multiple times. Pour the test fluid into the tester to the line and take off your radiator cap. Run your car until it's at the high side of normal and put the tester into your radiator filler neck. Depress the aspirator bulb over and over for two minutes and see if the blue fluid turns green or yellow. If it does, you have combustion/emission gases in the coolant and therefore a cracked/warped block/head or a bad head gasket. If it turns green or yellow, disconnect one head's spark plug wires and re-test. If you have the same happen, you have a problem with that head. Check the other too.

OK I don't know if this is your problem but my 92 sl2 is kinda the same way. my sl2s ECTS went out and it dose the same this is what it looks like you will have to remove the air duct to get to it and this is were it's located keep in mind there are two of them you want to unplug the one with two wires it is lower on the block. but do not remove it.

after unpluging it try starting your car if it starts them you will have to get a new ECTS Coolant Temp Sensor. btw don't drive around with it unpluged just becouse it runs dosen't mean you should use it like that.

Did you check fuses?

Check to see if the fan comes on.