Heat not reaching car interior.

There should be a value in line with the heater core. When this value opens it allows heated coolant to flow through the heater core giving you heat. It is either actived electrically or by vacuum and sometimes mechanically when the heater is turned on. If the value is worrking properly then the heater hose or core is clogged. You can flush them using a garden hose untill you get a good flow through it.
Hope this helps. BYM :o