Chevrolet Repair: Puzzled, vacuum controls, heater hoses

Question
1994 Chevy K-5 Blazer 350 5.7 liter engine
New Radiator, thermostat (tested) and heater core (tested)
Heater hoses and heater core are hot.  Damper door from hot to cold opening. Everything visible is functioning, but no heat in the cab.  Slight fluctiation in temp when changing temp from cold to hot.  A/C works fine.  Can you give me any suggestions?

Answer
Helen...i belive the ''blend ''door is stuck open on the ac side.If your heater core was replaced check those vacuum controls and vacuum servos that control the opening and closing of the plenum doors.If the hoses going into and out of the core are equally as hot,then you have good water flow. All you need is to control the air going over the core to extract heat..Check under that dash a second time...Best.  Let me ask you this....Was the heater core replaced or just tested...how was the test performed? Was the gpm flow accounted for?