Hello, I changed the thermostat earlier, because the heating remained cold. Now the heating goes again, but also after half an hour driving the cooler will not be warm. Temperature indicator is exactly in the middle, cooling liquid is on max. However, I have the feeling that in this hose the bottom of the cooler is no liquid in it. When I open the fan valve comes only little water. Can it be that due to the outside temperature minus 1 the engine despite new 90 degrees thermostat and indicator in the middle, the large circuit does not open? Motor 1.8 Year 2002 v40 Thanks Björn