There is a good chance that the coolant temperature sensor is the problem. On my car the cooling fan would not come on until the gauge was almost all the way up to the H. I found out in my case the coolant temperature sensor was cracked. Replacing it also improved my gas mileage since the old sensor was telling the computer the engine was cooler than it actually was. The sensor tells the computer what the temp of the coolant is, and the computer decides whether that temperature is hot enough to turn the fan on or not. This is usually
3/4 way up the gauge, in my experience, or with the A/C on, as someone else mentioned.
It is only about $10-$15 to replace. Just make sure if that's it, and if you replace it, that you replace the coolant temperature sensor and NOT the temperature sending unit for the gauge on the dash. They look similar and are located in the same general area on the engine- below the air intake.
Model confusion: the older model Saturns, at least, have no model designation anywhere on the car that I know of. You kind of have to know what you have. In the early 90s, if you had black bumpers and had no reflector between the taillights, you had the single overhead cam, less expensive version, usually designated S_1. If you had body color bumpers and had the reflector between the taillights, you had the dual overhead cam motor and had the more expensive version, designated S_2. If it was a coupe, the more expensive version had hidden headlamps, while the less expensive version had normal headlmps.
I did not know in the early years that the coupe only came in one version.
Actually I think the sedan came in 3 versions for a while- SL1, SL2, but also just "SL". This third option was very basic, I think, and was only available with the single overhead cam motor and was a stick shift.