Heating problems

Well, I was gonna post earlier, but i saw the thread on flushing the heater core so decided not to...
took the car for a spin to get the heat up (180* t-stat, temp got up to around there), parked it, and felt the two heater core hoses, both of which were warm (though the upper one that goes to the radiator by the cap was warmer it felt like).....
The switch thingy to control the heat and stuff moves without any problem, but it isnt loose at all (there is some resistance, but its not like stuck....)
I've replaced the radiator twice (First one blew up, second one leaked real bad)
I might still flush the heater core, i guess its worth a shot, though i really dont look forward to doing it in this weather (but if i wanna drive the car any time soon, i'd really like to have heat......kinda sad when its 30* outside and your thinking "Gee, its warm for a change!")
What else could it be? Before the first radiator blew up i got some heat...not much, but some, but only with it on A/C high or low, not on HTR or any of the other ones......true it was a lot warmer outside (though still PLEANTY cold), but why does it not blow any heat now? just cold air on any of the settings?
Suggestions/advice? Thanks

just be ready to pull the radiator hose if you use a flushing solution. The heater core could be filled with sealant, and could start sprouting leaks like crazy.

does it actually BLOW out??? check the blower/fan inside the dash for the heater, also... when sliding the heat control tab, you should hear the block-off plate moving in and out which allows heat to blow past... if you aren't hearing this.... you might consider getting up under the passanger side of the dash and investigating???

do you have the vac lines hooked up to the heat exchanger on the front part of the motor? this is needed to make the heat work properly. also make sure the stuff on the back of the control unit is all in tact as there is a vac unit that can come un hooked and cause this issue. its been a while since iv messed with the control unit so iv kinda forgotten what it looks like. also make sure you dont hear a hiss in the control unit as that might be a issue uin that area also. i have a hiss and havnt had the time to look at it which is where i "think" my eng vac loss is coming from.