Under the hood on the firewall there is a vacuum operated servo that opens the heated water to the heater core. Check to make sure that is working. The heater vents might not be oopening either.
Purging the air takes a little time, but when it is cool you can take the heater hose off where it goes into the servo on the firewall and run some water through the pipe with a water hose to force the air out of the core. Take the radiator cap off while doing this. If you can take the other hose off the other end of the heater core you can tell if it is clogged or not by how much flow of water comes out. Another thing is to pull the upper radiator hose off and hold it up while blocking off the thermostat end and pour water in the hose till it comes out the radiator, put the cap back on and then put the hose back on. Make sure your overflow reservoir is half full at least and that the radiator cap is good.
Let us know how it goes.
Russ
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