car heat issue
 

The car doesn't put out hot air when idling. Heater core was flushed but not sure if they bled the lines for air. It isn't low on coolant, you don't even have to be driving to make heat come out, just rev it up to around 2k rpm's and heat will begin to come out. I see one visible bleeder at least I think it is its one, above the intake manifold on the hard pipe. I also read that there is another bleeder on the heater core. I was wondering if the bleeder above the intake manifold would get all the air out by itself or would I have to find the bleeder on the heater core? And to bleed it should the car be up to temp and running when you loosen the bleeder? I am a novice at mechinacal work but I pick up on things pretty fast if anyone has some advice.