i removed the hose and flushed out the heater core and the fan blows only on high.I feel hot water going into the core but only cold water returning.thanks for all of your answers and help
You should try back flushing the heater core. Basically, disconnect the heater hoses from the heater core, install cut pieces of spare heater hose for ease of reach. Use the hose to flush one side of the heater core and then do the other. The idea is that deposits build up in the heater core an block the water flow. The same type of thing is done with a radiator. The heater core is a minature radiator of sorts. By reversing the normal flow of water, it loosens the stuck deposits and flushes them out. I would also inspect to see if your heater control is actually moving the linkage for allowing the hot water to enter into the heater core. If working correctly, both the incoming and outgoing heater hoses will be about the same temperature. This means that the water is flowing through the heater core and back into the cooling system. Good Luck.
It's probably a bad heater core if you've flushed it already. There should be hot tubes going in and coming out of the heater core. I'm having the same proble with my 1990 Colt.
hot in , cold out , that means the heat exchanger is working , try replacing the thermostat and the resistor that allows lower fan speed , you won't notice any heat on high until the engine is up to full temperature , good luck , keep on sluggin' that is a neat old car. p.s. you could trick the motor by blocking the rad. with cardboard , but cut a 6 inch hole centred on the fan and keep an eye on your temp gauge
