Heater Not Producing Much Heat

I have replaced the radiator, water pump, hoses, thermastat, gaskets. The heater inlet is hot, but the outlet is cold. The air conditioner seems to be working fine. The heater is not producing much heat at all. What could be the problem.

I have replaced the radiator, water pump, hoses, thermastat, gaskets. The heater inlet is hot, but the outlet is cold. The air conditioner seems to be working fine. The heater is not producing much heat at all. What could be the problem.
what make of unit is this . i had a 1988chevy pickup 350 with the same problem and found it to be the fitting coming out of engine to heater. it is a resticted fitting so to slow down water flow

Possible air pocket in the cooling system, but more likely it's a restricted heater core. Remove both heater hoses from the engine and flush with a garden hose in both directions until water comes out of the core clear. Reconnect the hoses, top off with coolant, bleed air from the system.

Possible air pocket in the cooling system, but more likely it's a restricted heater core. Remove both heater hoses from the engine and flush with a garden hose in both directions until water comes out of the core clear. Reconnect the hoses, top off with coolant, bleed air from the system.

Tried this. The hot air comes out for a short time and then the air turns cold. If the heater core needs replaced, what is the simpliest method to do this.

The easiest way is to hire it done. The least expensive way is remove the entire dash, (that's also the only way).

Dex-cool plug in the heater core.

Flush as directed in other post with garden hose.

Heat.