I have a 96 Monte Carlo z34 and have been having a lot of trouble with the engine overheating. I have replaced the water pump, thermostat and the relays. But still it will overheat. When the car overheats I check under the hood and the fans are not running. My dad was able to get them to run by wiring it to an external power source. So I don't knowif the fans are broken.I've taken it to a dealer for this problem and they said the car was running fine. Does anyone have any clue to what's going on? Please help.

It sure sounds like either a bad temp sensor or relay to me. The fans are not getting the signal to come on, so it almost has to be one of those.

Do the fans ever run?

When you change the water pump on a monte carlo you have to bleep the air out the system. I don't know where they're at on your engine, but there on there somewhere. When you do that it should stop overheating and problem solved. BTW the fans don't cut on unless it's reallllllllllly running hot. that's usally at the half way point or past.