Heater still doesn't work

I asked for help a few months ago concerning no heat on my 1978 Ford Granada. I did replace the thermostat but still had no heat. I then connected my compressor to the hose to the heater core and blew it out.
There is no blockage or leaks. Air came out of the return hose freely. I am going to dismantle the dash to get to the head and cables next. What I want to know is: 1. Is water always circulating through the heater core? If not, what allows the water to circulate? Turning the temperature adjust lever in conjunction with the selector lever? 2. Can the problem just be the core itself? Both hoses into and out of the core are hot and the air circulation does change when I move the selector lever to vent, ac, high/low, heat, and defrost.
Thank you
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warlock wrote:

Yes.
Doesn't sound like the problem.
Both hoses into and out of the core are hot
Good.
and the air

The problem is your temp lever/cable/control - this is the blend door control. Follow the cable from the temp control lever and watch or feel the action at the blend door bellcrank... it's probably not moving. If it is, you will have to take the heater box out, as the shaft has broken off the door/flap.
Rob
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wrote:

If both heater hoses are hot, you got coolant in the heater core. You probably got an air leak, or possibly a clog in the heater ducts. Mice can plug a duct.
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Just wondering what you mean by core? Water always circulates through the inner radiator - but saying that there is a valve (heater hot /cold) that allows hot water to flow. Check the valve is working properly....
I had the same problem with a cortina some years back.
check:-
1...Make sure you check the thermostat for correct operation (fit a 92% stat) 2...As above check the heater control valve is working correctly 3...Check internal radiator for leaks blockage (not sure where it is a on a granny - but on the cortina it was under the bonnet near the bulkhead) 4...The water pumps are normally OK but check this also (though if the pump was knackered the car would overheat) 5...Also remember to check the air ducts for blockage 6...Also check the fan - maybe it is running all the time (electric) - if it is a viscous fan make sure it is free to turn.
Fluke
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As posted below, sounds like the post on the mixture door in the heater air plenum. I had one break off on my Aerostar. Let us know if that is what it proves to be. Since I replaced mine, I've been parking the car with the door in the defrost position, while it is still warm. I believe mine broke when adjustments were attempted while the car was cold in freezing temperatures and the plastic was brittle. This seems to be a common problem. Can anyone else attest to this part breaking in unwarmed-up cars in freezing temperatures?
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