I just replaced the thermostat in my '88 HB. Afterwards I bleed the cooling system and everything you are suppose to do. I let it run for about 30 minutes and the heat hand raises to where it's suppose to. When I turn the heater on only cold air blows out. Could it be the heater core? Also, the lower radiator hose is not getting cold and the upper radiator hose get a little warm but not that bad. The radiator is not getting hot either.

 

did you have problems with the heat before the thermostat change?

if you look inside the engine bay where the coolant lines go into the fire wall there should be a little lever attached to it. See if you cant open that lever manually.

 

when I bought the car a while back there was no thermostat in there.....I'll check the lever in the morning. Thanks