sure sounds like an air pocket blocking coolant from flowing thru the heater core. Try bleeding it again, heater on full blast. You certainly wouldn't be the first to have to bleed a Grand Am repeatedly to clear out the air pockets. And, its a cheap option. Oh, and the computer can't "tell" thermostat to open, thermostat is a mechanical device that only opens/closes based on temp of coolant it's exposed to.
Hope this helps.