I did replace the pollen filter 4 weeks ago, but I don't know if it has been re-gassed by the previous owner, it hasn't been done by me in the year I've owned it. I can't explain why the air doesn't flow through the vents as it should, seems odd, and the fact that the air con was OK this morning suggests a possible leak. I guess as Brian says, I need to take it to a specialist, and fear not, Kwick Fit will never see my money again!