I would first verify that the engine is actually warming up with a scan tool and/or a temp gun on the cylinder head. Should be at least 180 F. Cooling fans should come on around 220 F.
There is a shut off valve on heater hose that are prone to fail on hondas. Make sure it's not seized, and that it is open, opens. Download service manual if you haven't.
With the blower on and the engine warmed up you should be able to feel a difference in temperature between the inlet and outlet heater hose. If they are the same temperature I would suspect the in line valve. If it is good try flushing the heater core.
Also with the engine warm and the blower on, move the temperature from hot to cold, and back. You should feel some difference in temperature from vents. If there is no change at all in temperature i would make sure blend door actuator is working.
Probably valve in heater hose stuck closed.
There is a shut off valve on heater hose that are prone to fail on hondas. Make sure it's not seized, and that it is open, opens. Download service manual if you haven't.
With the blower on and the engine warmed up you should be able to feel a difference in temperature between the inlet and outlet heater hose. If they are the same temperature I would suspect the in line valve. If it is good try flushing the heater core.
Also with the engine warm and the blower on, move the temperature from hot to cold, and back. You should feel some difference in temperature from vents. If there is no change at all in temperature i would make sure blend door actuator is working.
Probably valve in heater hose stuck closed.
