The fans will come on with the ac running, but will not turn on when it is pushing regular air? I have changed the thermostat, and still get overheating? I couldn't get any coolant through bleeder valve with car running, post- thermostat replacement. Test drove to work, and idled for a long time with gauge remaining good. Wife runs it to hot on gauge within 4 blocks. Fans work when I run ac, but not regular circulation?
When engine is running, opening the bleeder valve would only allow thw water pump to suck in air and result in air in system.
With engine off, release bleeder valve and top up coolant till it flows out through bleeder valve and air bubbles stops. Retighten bleeder valve and top up coolant. Start engine with radiator cap off and when coolant level drops, top up coolant until it is constant.
Close radiator cap aand run engine, with heater turned to maximum, till operating temperature. Stop engine and wait for it to cool before rechecking the coolant level. Top up if necessary.
As to the fans not running when temperature heats up, fan relays are controlled by the PCM. Have the Engine Coolant Temperature Sensor checked.