Hi all. Last week my water expansion bottle burst, replaced it with a new one. Since then, my temp warning light comes on now and again, as soon as I put my heater on full blast, it goes off. It helps if I keep my heater on a little, but then I get to hot in the car. Have I got an airlock do you think ? If so how do I clear it. I am not to technical with cars. Any help at all please.It is a 2003 ford ka with the 1.3 duratec engine. Many Thanks.