Originally Posted by
nipagu7
mudski maybe you have a thermostat that is stuck open , so that in winter the coolant is circulating too fast and cooling the motor down and in summer if the coolant circulates to fast it cannot shed heat quick enough as it moves through the radiator to fast ( although this usually only happens when the thermostat is completely removed ) . mb do you have a cabin pollen filter , just thinking it might be blocked , you might still have reasonable air flow as there might be a bypass around the filter and possibly the heater core , its been a while but when i fitted my cabin pollen filter i think i remember that air was able to flow under it . so basically you might not be getting enough air flow thru the heater core to heat the cabin .