Change the switches. They are only like 20 or 30 bucks each. That was the culprit when I had that problem. and they are quick and easy to change yourself. Also, if your car is getting hot, turn the A/C on. If the switches are bad, they won't turn on the radiator fan, so turning on the A/C will at least make that fan turn on, so it helps to keep the temp out of dangerous levels.