I have a 1987 Chrysler New Yorker and the heater just quit blowing hot air. I've checked the thermostat, replaced the ac/heater valve (that plastic valve in the engine compartment), and flushed the heater core. Both the intake and out take hoses for the heater are hot to the touch, so it appears as though water is circulating through the heater core. I've also checked the vacuum lines. I don't know were else to check. I'm looking for any other solutions to this problem. Winter mornings, even here on the Oregon coast can be a bit cool. Thanks!

sounds like a vacuum mode door that control the heat is stuck closed.

Thanks for the reply. I'll check that out. Do you know if there's any way around pulling everything apart to get to the door to check it?

the only way to check those doors is to pull out the dashboard, and take the heater case out that's about the only way to check that.