If you have a visible chip on the shaft of the key you probably need to change the lock cylinder. If there is no visible chip in the shaft of the key but you have a large plastic head on your key, you probably need a new lock cylinder halo ring.
I would test the A/C compressor clutch coil first , easiest to do . If the electromagnet clutch coil is bad ,the compressor won't engage . Pull the A/C compressor clutch relay an jump pin's 30 & 87 , where the relay plug's into the fuse box . If pin 30 has B+ voltage ,pin 87 sends that B+ voltage to energize the clutch coil . These clutch coil's can go bad . You could also check the cooling fan this way , pull the cooling fan relay an take a piece of wire an jump pin's 30 & 87 .If fan is good it will run . Do you know how relay's work ?
VEHICLE RELAYS Operation Diagnosis
The PCM controls both relay's by supplying a ground to energize the relay .
Is the check engine light on ?
Do you know what a wiring diagram is ? How to use one along with a DVOM - digital volt ohm meter to test automotive electrical circuits ? Not guessing ? This is how an automotive technician would solve this problem , hooking up a scan tool an checking for code's ,using bi-direction control of scan tool to manually try to turn on coolant fan ,A/C compressor .....
Free wiring diagrams here http://www.bbbind.com/free_tsb.html
Enter vehicle info. year , make , model an engine size. Under system click on engine ,then under subsystem click on cooling fans ,check the electrical circuit's .
saturns use a spin on transmission filter,similar to the motor oil filter.after-market filters like FRAM or PUROLATER are as good or better than dealer parts and likely less expensive.transmission fluid is drained from the plug in the pan,again,like the motor oil.
Voltage drop testing the starter electrical circuit would be a good first step , ruling out the cable's connections an ground !
Starter Voltage Drop If this doesn't find a problem ,then check the control side . Ignition switch , when it won't start check for Battery voltage at the connection at the starter solenoid "S" terminal .
How to voltage drop test starter motor circuit
You need to have the fault codes read with a OBD2 code reader or scanner, that is how you find out what system in the computer controlled engine is acting up.
Does the engine reach normal operating temp? Do you live in an extremely cold region? Are the heater hoses hot? Also, there could be a problem with temp door, under the dash.