Anyone, I got a 1992 acura legend with 143k, for the pass few weeks am getting warm air then i put the heat on, so i went to the dealer and got some coolant and a thermostat and replace them, and still having the some problem. what could this been?

the heater core is probably getting full of garbage or the coolant lines running to it are plugged

The valve going to the heater core is probably stuck open

The valve going to the heater core is probably stuck open

I checked all that stuff and still have the same problem