Honda Car Forum

Hi, my accord 91 EX has 220K miles. In the winter, if the car is parked and Idle, the engine temperature and the heater seem working fine - the temperature gage is close to the midle. However, If I drive on the highway, The temperature gage drops to C (bottom), The engine idle goes up, and there is no or very litle heat. I rememeber I replaced new dealer thermostat last year.

Thanks for all advice.