If there is no coolant then how will it keep cool?
But if you have coolant and fan is working and still overheating then check thermostat or water pump or blocked radiator

 

you need to test/fix the fan or else you'll just keep overheating

 

Found another issue and fixed it today. The hose inside the reservoir had been detached and was sitting at the bottom. I dumped the reservoir fluid into the radiator and filled the radiator the rest of the way up and refilled the reservoir. Took the car for a test drive and while it did last longer before it overheated it eventually red lined. I checked the fan by turning the AC on and it does run. However, I have not seen it run with the AC off. Any more help available?

 

When the engine is cold, start the car and turn on the a/c. Do both fans turn on?

Running the car while it is hot is not good for the engine. If you start to overheat, turn on the heat full blast with the recirculate turned off to help cool the car.

 

Yes, both fans turn on. But I have not seen the fans turn on just to cool the radiator without the AC.

 

There is Fuse no. 9 (20A) and Fuse no. 11 (20A), located in the under-hood fuse/relay box, in the circuit. You mentioned you replaced one of the 20A fuse, just for giggles, check fuse no. 11. The fan turning on with the AC means Fuse no. 9 is okay.

IIRC, the radiator fan switch (ECT sensor 2) is located at the bottom of your radiator (to the left of the drain petcock). Check the wiring and connector at the ECT sensor. On second thought, I don't think it is the wiring or connector though, as usually a trouble code would show up if that was the case. Maybe be a switch problem.

 

Check it anyway... I think in 2003 that switch in the lower tank of the radiator is still a simple fan switch so it won't trigger a CEL. Wasn't until 2005-ish before that became a "sensor".

 

Fuse 9 and 11 are not blown. They are both 20 amp fuses. I looked for a switch by the bottom of the radiator and found 3 connections. One went to the AC compressor. One was on the driver side heading aft. And the last I have no idea. The AC compressor wire looks okay but you can see the blue of the outer sheath. I checked for nicks or shorts and no cigar.


Exactly where is the switch and how should I check it? I have a multimeter if that helps.

 

For the fan switch - see if this helps

 

Found the switch and it looks okay. I filled the car today with peak coolant(going to flush and get type 2 soon) and took it for a drive with no overheat. Got back and the reservoir was empty. So I'm thinking either:

There is a lot of air in the system from when I took the coolant lines off the throttle body while replacing the starter.
or
There is a leak in the coolant system.
or
Coolant is leaking into the engine block.

What do you think?
How can I verify any claims?