hi new to this site and just bought myself a new discovery (1995 300 tdi) and it drives fine on long or short journeys if the heater knobs are on hot with fans off..... but if i turn them to cold still with fans off the tempreture rise's very slowly until almost in the red but if i turn heater knobs to hot again it will go back slowly to halfway and stay there until you move heater knobs to cold again does anyone know of this problem and any known fixes thanks chris.