rad doesn't get warm

my '96 cavalier heated up the other day so we changed the thermostat. the car still heated up but no heat came out inside the car. we vented the steel line and finally got heat inside the car. we also vented the plug beside the engine but the rad fan still wont' come on. the rad still is cold on both hoses as well. we pulled the water pump out and its fine. the guage goes up and engine will overheat if we kept it running. any ideas? is it an air lock? rad plugged? we used an air compressor to blow through the lines and it spews out the other hose. any ideas we really help

either pump is not fine and not moving water or there is a big blockage in a hose, in engine or somewhere is system. is NOT reccomended for long term, but try removing thermostat and see if problem goes away.