Diagnosing no heat

[Formula413]

My car has little to no heat. I opened up the heater box today and felt the heater core, it was just barely warm to the touch with the engine at ~200*. Is there anything else I should check before I slap a new one in there? Could the old one be flushed effectively? I was looking at a diagram of the cooling system and I noticed there is a part on the hose leading to the core called a "flow restrictor", is that a mechanical part that could fail? Or just a fixed restrictor?

[BOTTLEDZ28]

Hook up a garden hose to one of the rubber coolant hoses going into it and flush it out. You will have to pull the other rubber hose off and let it drain under the car.

[My84Z]

What Brad said dexcool gets very sludgy

[irockidz28]

^x3

[ILuvPizzaTimes10]

all of the above! except i use air. never really liked the idea of using 40+PSI into a system designed for 16.

[Formula413]

Yeah if I flush it with a hose I will turn the water way down, don't want to blow anything open. Might change some of the hoses while I got it drained. Probably makes sense to flush it in reverse right?

[My84Z]

Correct

[irockidz28]

i did it both ways when i did it on the s10 figured it couldnt hurt

[Formula413]

Did a lot of crud come out when you flushed it?

[ILuvPizzaTimes10]

you wanna go backwards first. if you were to flush in the normal direction of flow you can plug it up worse. then you mine as well change the heater core!