blower not blowing warm or hot air when on heat or defrost & heat is switch on

Yes. It was working. Also with fan off and temp pushed to the hot side, seems to be some warm air flowing through. But when fan is turned up it just has cool air blowing thru defroster or heat venfs.

Your heater core is not getting hot enough. Either the core is restricted or the water is not flowing to the core. The water temperature up high enough.