Heater works & engine temp good when parked,& driving no hot air & car runs cold on 1997 Honda Civic

At speed I have no heat or minimal heat and engine temperature is cold. When I'm parked the engine temperature warms and I get hot air? What is causing this?

Asked by for the 1997 Honda Civic
3 answers 2 comments
It's common for the thermostats to stick in the open position on these engines. Remove the thermostat and inspect it.
It's likely the thermostat is weak. Try replacing that first.
I tapped where the thermostat is with the butt end of a ratchet and it works a little better but not great. So more than likely is the thermostat right?
ck coolant level to start with
Coolant is full and checked it's good to -10