I have a 97 altima 2.4 twin cam and I just did the thermostat and the car doesn't over heat. The heat was blowing hot. Then I went to work and it seemed a little cool then it went hot again. The fans seem to click on and off repeatedly. I know there is air in the system but I am looking for that bleeder valve and I cant seem to find it.
Not all engines have a bleeder valve. If the heater is working and the engine isn't overheating, you know the coolant is circulating. That means as long as you keep the reservoir full, any air will be expelled into the reservoir. If you still want to bleed the system manually, look for the coolant temperature sensor or a threaded plug to unscrew. They will be on or near the thermostat housing.