I have a 1994. The ac is working today and the temperature never went past the 1/2 way point today...but then again the day was about 5-10degrees cooler...I havent tried to let the car run on idle to see if the temp.
will drop at the 240 mark when the fans usually come on...ill try it on my next break for school in about 20mins

 

Alright...well I havent done anything to my car and today is the 2nd day
that my car doesnt even get close to the 1/2 mark and i live in the san fernando valley in california with stop and go traffic to work, lunch break, and home and to school...i am also running my ac on max most of the time since it started working out of the blue.....what happened?...only the car knows but i am happy right now....

either way tomorrow i am changing my tranny fluid, engine oil, engine and tranny filter, coolant, add that additive to the coolant that reduces the coolant 10 degrees (i think its that much) and maybe add an air foil for the hell of it...oh yeah and the t-stat too and maybe radiator cap.....

by the way...does anyone know the operations on the fan...
is one fan always running or do they both come on at the set temperature? do the fans run when the ac is running???....
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thanks for the help...
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I'll just let you know about my problem.

First the car overheated out of nowhere, as I saw it go up all the way I shut if off and let it cool, and it seemed fine. Seemed like a fluke.

Then I started noticing the temp going up to like 230 and staying around there if I had the car on for a while at slow speeds.

Then after a few times to the track with the car running warmer then ussual, it became where the car was always low on coolant, and it wouldnt stay cool unless I filled it up every few days.

Then it got bad, and it wouldnt stay cool unless I bled the system almost every time I started it up, otherwise it would get super hot.

Then I replaced, radiator cap, thermostat, fan relays, had radiator taken apart and cleaned, new coolant, the whole deal. No dice, still acted the same.

Then I pulled the water pump, looked fine

So then I pulled the plugs, one seemed slightly cleaner then the others, I pulled the head and found a nice clean piston, a gross looking orange residue on the head, and a blown head gasket that was leaking into the cylinder.

So now I am pulling the motor out, re-bearing it (just in case), new gaskets all around, new optispark, new csi water pump, hotcam and 1.6 r/r's and fresh valve job on the heads. Then I will bolt it up and have fun again.

Sorry to tell you, but your problem seems alot like mine. I also cooled it by rev'ing it up, but it would heat back up.

I expected it to be like night and day, but to be honest, even with the blown h/g I could still keep it cool enough for a night at the track, running only about a tenth off my regular times. I could have sworn that wasnt the problem, I even had a guy presurize the cooling system, only lost 1lbs in like 10 mins, and the guy said it was normal for that to happen. Nope, BLOWN HEADGASKET w/absolutly no common signs.

Hope thats not your problem, but figured I'd let you know about mine.

 

How difficult is it to do what you did ...
removing the cover and checking the cylinder heads??? what kind of tools are required???....

 

well i changed my t-stat,
engine oil and tranny oil (drop the pan only) and also flushed coolant out again and ....its still doing the same thing...
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I have a question though, i had the car running for about 2 mins and i removed the radiator cap and the radiator was not fully topped off and i was
able to see 1/2 of those little round thing inside the radiator and the reservoir was topped off but never shot water back into the radiator and i thought this is what it was for...does it have some type of pump??? is it possible the cap
on the reservoir can wear out too like a radiator cap??...

by the way, ROyal purple oil...very well! I used it on the engine and tranny and my cars runs smoother and the oil pressure is higher(which is a problem i had with low oil pressure) and when it shifts it pulls nicely with the shift kit...feels just like when i got my car back with a tranny rebuilt 1 yr ago

 

Get a new GM radiator cap and bleed the system correctly, this should fix you up from what I have read. More info send PM.

 

SO all that i Did on the car worked...not sure which one but it worked and the car is running good and i have not seen it overheat since...i am pretty sure it had to do with the bleeding and mixture of coolant along with the amount of water in the reservoir....on cold i filled it up to the cold mark...no problems since and this was about 1month ago...ohh..and i didnt change the cap. i made sure the cap TVS was pointing towards the passenger and RC24 towards the headlights....

 

Your fans automatically come on and stay on while you have a check engine light.