Overheating 2000 grand am

Hi, I have a 2000 grand am v6 3.4, I noticed that my coolant was running low and after filling it, it all leake out again, I figured out that this was due to the car over heating and the coolent boiling out of the escape hose on the resovoir. After a little testing we discovered that the fans where not turning on. We tested the fan motors and they bothed worked, we then replaced the coolent tempature gauge sending unit, also with no help. We have also changed the relays with no help there either. If anyone can help I would appreciate it. Bill

I was reading on the forum that when you turn your AC on that the fans should also turn on, so i went to see if they did and I got no response when i turned the ac on.

I noticed the fans on my 2000 would only kick in if the engine was running into the yellow or halfway to the yellow from optimum driving temps. If you turn your Defrost on full blast full heat it will cool the engine quicker. If you have high miles on your 2000 ga maybe its time to flush the cooling system and replace the thermostat. One thing for sure , put a big piece of cardboard under the engine at night and pull it out in the morning , if theres reddish orange on the cardboard you got a coolent leak. Have a shop do a pressure test to find the leaks. I hope its not a leak for your sake I had a leak costed 700 bucks in parts and labour to replace those gaskets.

I was reading some more on the fans, and from what everyone tells me they wont come on till around 220-230, I have never let my car get that hot, when I told my friend this and the fact that the coolant is boiling over the resovoir he gave me the idea to check the cap. So I am going to replace it tomorrow and post the results.

Just to let everyone who cares know, the new cap did work.