To start I have a 89 Firebird Formula 350, with the dual electronic fan. Yesterday On the way home I noticed temperature started rising to near overheating level. Since I was close enough I simply popped the hood and drove it home with the hood simply popped allowing air to flow in cooling the car down. This seemed to work as the temp dropped back into normal range and I was able to get back home safely and with no damage to the car. Upon inpspection I noticed the fans were turning on when they were suppose to. Called my uncle who is a mechanic and asked him what it could be. He had me connect a wire from one of the fans to the positive to check if infact it was the actual fan/s. In doing this the fan came on and I found the fan/s were good,Or so he says and I hope. He told me it could be 1 of 3 things. The relay by the firewall, the thermostat, or some fan temp switch(I think thats what its called. When bought it,it looked like a gold screw/bolt with a plastic piece coming out of the head or top of it). As this happened at my Fiance's house I havent had the chance to change the thermostat and the "fan temp switch",I think thats whats its called (its proper name would be helpful) wasnt even on the box and the guy at autozone knew what it was but I forgot to ask for its proper name if I have the name wrong to begin with). Ayways I changed that one relay up by the firewall. Is there another? That didnt work So Im gonna say that wasnt the problem. Tommorow Ill try the termostat and "fan temp switch". What Im curious about is there any other relay's or anything in general that would cause the fans not to come on if neither of these two fixes my problem? Any and all help would be greatly appreciated. When offer up your tips advice or knowledge try to be as desciptive as possible with locations names etc... Im by no means a mechanic I have a somewhat general understanding of everything and thats about it. Never dealt with cooling before on this car. Thanks.

Also another question.....sorry...My coolant reservoir was damaged because of the heat that occured when the fans didnt come on. It got a crack. Could JB weld be used on this crack to seal it until I get a new one? I tried a bunch of stores and they just have those universal ones. Id rather have the vehicle specific one from another car or reproduction.

im not sure bout jb weld never used it b4..but this is a great site to buy from:

http://tpiparts.net/inc/sdetail/470

sounds like it may be the fan switch in the pass side head near the back of the motor.

compare the part you have with the pictures in the links i give you.

here is the fan switch that should be in the pass side head



pay close attention to the shape of the black plastic piece...

if ur part looks like this:



then you bought a coolant temperature sensor that goes into the intake manifold underneath the throttle body

if u have the dual fan then i believe you need to replace the fan switch.

checking the thermostat is easy, let the car idle and at about 190-200 degrees check to see if the upper rad hose is getting hot. if not, shut it off and replace the thermostat.

I am overheating also but I'll fill in what I know about our cars. There are two relays on the passenger side of the radiator next to the purge canister. The top one also controls a fan. I had to run a wire from the fan temp sensor in the head directly to this relay because a former owner had wired it up wrong(melted wires from the freaking heat??).
Right now only my driver side fan is coming on when it hits the 200 mark(aftermarket switch in head). The passenger side doesn't seem to want to come on at all. It is also running around 210 while going down the road which tells me the fans are not my problem.
Can someone tell me if this sounds like a water pump or some other problem?
Sorry to hijack thread but since we both have 89 formula 350s we should get some answers.